Abstract: Abstract: A field trial indicated that plant P content did not significantly change in all growth stages, while NK contents kept declining and NPK uptake kept increasing from early to late stages. Addition of NK fertilizers obviously plant NK contents and NPK uptake, however, addition of P did not significantly influence plant P content and uptake. Based on the fact that plant NK contents at seedling were about 6 times as those at harvesting, and launching of NK uptake occurred during silking, it is believed that the two stages should be the most sensitive nutrition periods for sweet corn production, thus demanding sufficient nutrition supply from the soil.