The slogans - one of which said "all efforts on economy" - are in line with Kim's new political priority outlined earlier this year before he met Trump.
With tensions once again on the rise, a parade featuring the very missiles that so unnerved Trump past year, and led to a risky volley of insults from both leaders, could be seen as a deliberate provocation.
The procession also celebrated civilian groups such as nurses, students and construction workers in an effort to emphasize the country's economy.
"(China) hopes North Korea and the United States will implement their common understanding (made) in their bilateral summit and keep to the good trend of peace and dialogue", the Chinese official said, adding that China wants to play a "constructive role" in resolving Korean Peninsula issues politically together with other concerned nations.
The non-provocative nature of the display earned a tweet from Trump, who called it a "big and very positive statement from North Korea". "Thank you To Chairman Kim", Trump wrote.
The parade was more low key than a parade staged in April 2017 that featured an array of ballistic missiles, exacerbating tensions with the United States.
Floats on unification also passed by a throng of North Koreans waving unified Korea flags.
Both the Mass Games and the military parade have been criticised by human rights advocates and North Korean defectors for the pressure placed on performers and for painting a distorted picture of the country through stage-managed displays.
While Kim did not speak, the head of North Korea's parliament Kim Yong Nam stressed in an opening speech that Pyongyang has achieved military power and that the country's new focus would be on economic development.More news: Syria's Idlib 'Cannot Be a Slaughter'
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But this time there was no real trace of the country's nuclear weapons program that has been characteristic of past parades, including one before the Winter Olympics in February.
The theme for the celebrations this year was economic development and unifying the Korean peninsula, divided since World War Two.
Thousands of dancers, gymnasts, martial artists and singers acted out scenes addressing familiar themes from North Korean propaganda, including the country's struggles to recover from the 1950-1953 Korean War, and a starvation in the 1990s.
It would be a three-stage rocket which would the largest of its kind ever launched by North Korea.
North Korea's desire to use the performance to attract worldwide attention was clear, said Gianni Merlo, the Italian head of the global Sports Press Association, who said he was invited to attend the events by the North Korean government. "Unification is the only way Koreans can survive", read a Sunday editorial in communist-party newspaper Rodong Sinmun.
Despite no agreement yet between Pyongyang and Washington on the denuclearization process the two agreed to at their landmark Singapore summit in June, and with Pyongyang demanding the USA agree to a peace treaty to end the 1950-53 Korean War, there have, over the last week, been some encouraging signals.
The mass games involve tens of thousands of people holding up placards or dancing in precise unison and are meant to be a display of national unity.
A week before the third summit between the two Koreas in five months begins in Pyongyang, Chinese President Xi Jinping, Japanese Prime Minister Shinzo Abe and South Korea's Prime Minister Lee Nak-yeon converge on Vladivostok for an economic forum held September 11-13.
The mass games performances are expected to continue for the next month or so, with tickets for foreigners starting at just over $100 and going up to more than $800 per seat.