Abstract: To increase the output and profitability of alfalfa seeds, subsurface drip irrigation (SDI) was introduced into a production experiment of alfalfa seeds. Through the study of salt distribution of SDI in the soil and the growth characteristics of alfalfa, the possible uses and effectiveness in alfalfa production were explored. The biggest moisture content of SDI was 65%-80% of the soil moisture (W1) and the biggest radius was 50 cm horizontally and 20 cm vertically enabling water to reach the roots of alfalfa. The W1 root weight was significantly (P<0.01) higher (25.09 g) than that of the other treatments and the root weight sequence was W1＞CK (flooding irrigation)＞W2 (50%-65% of the soil moisture)＞W3 (35%-50% of the soil moisture). The seed yield of W1 was significantly (P<0.01) higher (909.62 kg/ha), than that of the CK (611.39 kg/ha). The application of SDI in alfalfa production could increase seed yields.