In order to understand the effects of cold storage on the nitrite and nitrate contents of four kinds of green vegetables and evaluate the safety of cold storage processing.Methods Diazotization-coupling reaction spectro-photometer and tnymol spectrophotometer method were used to analysis the nitrite and nitrate contents in four kinds of green vegetables including lettuce, spinach, leaf lettuce and endive in four days stored at 4 ℃. Results The results indicated that nitrite content in lettuce and endive rose up through storage time. The nitrite content in spinach and leaf lettuce reached the maximum on the second and third day, respectively. Then the content began to decrease. However, it rose again on the fourth day in spinach. The peak value of nitrite in the vegetables in four days was 0.419 4 mg/kg (in cucumber) which was far less than the limit of 4 mg/kg. Nitrate content in endive and leaf lettuce was gradually increasing through four days. The nitrate content in spinach reached 418.48 mg/kg on the second day, but decreased to 20.83 mg/kg a few days later. The nitrate content in lettuce reached 317.26 mg/kg on the third day and decreased later. The contents of nitrate in four vegetables were within the safety range (432 mg/kg). Conclusion Compared with nitrite, four vegetables had more nitrates in four days. Meanwhile, contents of nitrate were all in the safety range. Cold storage could effectively slow down the increase of nitrite and nitrate contents in vegetables.