According to the data surveyed and released respectively by 3 official authorities including the Bureau of Agricultural Economics under US Department of Agriculture, Bureau of Labor Statistics under US Department of Labor and the Census Bureau under US Department of Commerce, the agricultural population in the United States had a sharp decrease in 1910-1970, and the population structure had completed the transition from agricultural population to industrial population. But there are also some omissions in the official statistical data, mainly including the “agricultural service” workers, floating agricultural population, illegal immigrants and child laborers. These 4 kinds of labor force population that directly or indirectly engage in farm production are not included in the agricultural population of the United States. For the purpose of exaggerating agricultural labor productivity and covering up exploitation from the perspective of the official US authorities and due to limited statistical methods as well as complicated conditions, some data problems including great difference in agricultural population statistics and inaccurate absolute quantity have been caused.