In this study, vegetation data in different precipitation years (rainy years, normal years and dry years) were adopted from the long term experimental platform of Stipa breviflora desert steppe in Inner Mongolia from 2004 to 2015. Interspecific relationships among 7 major plant species (21 pairs) and their response to the change of precipitation years were studied. The overall association among species was measured by variance ratio. Based on χ² test, pairspecies association was measured. Association coefficient (AC) was calculated to confirm positive or negative associations. Percentage of cooccurrence (PC), Ochiai index (OI), Dice index (DI) were calculated to analyse the probability of pairspecies concomitant occurrence. The aim is to clarify the relationship between the main species in the desert steppe and reveal the mechanism of the influence of precipitation on the interaction between the populations. The results are as follows: (1) the average of species number in sample plots reached the maximum in normal years. The overall association among species was significantly positive in rainy years. It was not significant positive in normal years and not significant negative in dry years. The result showed that the decrease of annual precipitation changed the relationship of main species from coexistence to competition. (2) The change of precipitation years changed some of pairspecies associations. The species pairs with positive association in rainy years accounted for 57.1%. It fell to 52.4% in normal years and 33.3% in dry years. It showed that drought stress led to the decreasing of coexistence pairs and the increasing of competition pairs. (3) The change of precipitation years mainly affected the percentage of cooccurrence of Caragana stenophylla and other species. It was the largest in normal years. There was no effect on the positive interaction among the other pairs.