Yu was among the tens of thousands of guerrillas and their supporters who from 1934 joined the Long March in an effort to break through the Kuomintang blockades around the Communist base in the south.

In the following year, the discovery of huge oil reserves in Daqing in the desolate wastes of north-eastern China gave him a mission for which he is much remembered.

[3]: 52  During its 1960 construction as part of the Great Leap Forward, Yu mobilized workers building the Daqing oil field through ideological motivation instead of material incentives, focusing enthusiasm, energy, and resources to complete a rapid industrialization project.

[3]: 52–53  Yu read Mao Zedong's writing to workers, urging them to engage in the hard labor at hand out of commitment to the building of Chinese socialism.

[3]: 53 The successful construction of the Daqing oil field despite harsh weather conditions and supply limitations became a model held up by the Communist Party as an example during subsequent industrialization campaigns.

[3]: 54  Daqing oil field produced the famous Maoist icon Iron Man Wang, who, in order to stop a blow-out, leapt into a pool of liquid concrete to mix it using his own body.

That year, Yu was moved into the most important government ministry related to the economy, the State Planning Commission, as vice director.

[2]: 103 In 1965, Mao made Yu the top drafter of the Third Five Year Plan and put him in charge of relocating major industries to the remote hinterland of south-western China.

[2]: 104 Yu was involved in the February Countercurrent of 1967, an intra-party conflict in which a group of military leaders opposed the direction of the Cultural Revolution and the Gang of Four.

[2]: 154  The radical side prevailed in the dispute and several leaders who had been a part of the February Countercurrent were required to take leaves of absence and make self-criticisms.

These officials were essentially Stalinists in their economic thinking, favoring central planning and heavy industry - a strategy that clashed with that of the ascendant Deng.