Abstract: The February orchid (Orychophragmus violaceus)spring maize rotation system is established to resolve the problems caused by the expansion of fallow fields in North China. Based on a sitespecific experiment, temporal and spatial variations of soil NO₃^--N were investigated during the period from February orchid incorporation to maize harvest. The results showed that the nitrate content in soil profiles not only showed a temporal characteristic, i.e., increasing at the beginning of the maize season and decreasing then after, but also showed a spatial characteristic, i.e., the gradual occurrence of the peak of nitrate content from shallower to deeper layer with the growth season of maize. Meanwhile, incorporation of February orchid could affect temporal and spatial variations of soil NO₃^--N. February orchid planting reduced the soil NO₃^--N accumulation in the profile of 0-180 cm. After incorporation of February orchid, similar characteristics were observed at the seedling and bell stages of maize, i.e., the soil NO₃^--N mainly stayed in the profile of 0-20 cm, and NO₃^--N concentrations in the treatments with February orchid were higher in 0-100 cm layer and lower in 100-180 cm layer than those of the treatments without February orchid. After tasseling stage, opposite phenomena were found, and the soil NO₃^--N content was all relative low. Overall, incorporation of February orchid could increase the storage capacity of soil NO₃^--N in the profile of 0-180 cm.