Five fields were selected from Xining City by stratified cluster sampling method for the survey. 4589 people above 3 years old were examined for nematode infections using Kato-Katz method and children under 12 years old were detected for pinworm infection using transparent tape method from June to August in 2011. The results showed that the total nematode infection rate was 3.0% (136/4 589) with the highest of 3.8% (123/3284) in rural area. The major species was Ascaris lumbricoides, and the infection rate in 15-20 age group was 1.5% (4/264), which was significantly lower than that of the age groups of 60-70 (6.9%, 23/335), above 70 (5.3%, 6/114) and of 10-15 (5.1%, 19/372)(P<0.05). The prevalence of A. lumbricoides among the preschool children (9.5%, 12/127) was statistically higher than those in other occupation groups (P<0.05), and the infection rate showed no statistical significance by gender, ethnic and degree of education (P>0.05). Pinworm infection in children under 12 years old was only 0.5% (2/437).