Objective: To understand indoor air quality in middle and primary schools of Hangzhou in autumn and winter seasons, and to provide references of promoting indoor air quality of schools. Methods: Totally 33 classrooms of 11 schools in urban area were selected into study during Sept.2018 to Jan.2019. Daily measurements of PM2.5 and CO2 were performed in selected classes during school working time by air quality monitors. Totally, monitoring data of 35 964 hours were analyzed using univariate and multiplicity analysis for PM2.5 and CO2 level, variability and possible influence factors. Results: In autumn and winter, hourly average values of classroom PM2.5 and CO2 concentration level in Hangzhou were between 35.30 to 74.65 μg/m3 and between 949.17 to 2 029.98 mg/m3, respectively. The concentration levels of PM2.5 and CO2 were higher with the temperature(F=1 412.84, 775.66, P<0.01). No statistical significance was be found for the difference of PM2.5 concentration among monitoring times. Wave changes in CO2 were observed with time variation PM2.5 and CO2 concentration level of 68.42% monitoring times was complied with standards. School type and temperature correlated with PM2.5 concentration level. The PM2.5 concentration level in senior high school was higher than that in junior high school, while the value in primary school was the minimum(β=0.44, P<0.01). And the PM2.5 concentration increased with the temperature decreased(β=8.31, P<0.01). School type, temperature and monitoring time correlated with CO2 concentration level. CO2 concentration increased with the increase of grade, decrease in temperature and later time during the day(β=213.64, 162.38, P<0.01). The CO2 concentration level in later monitoring time was lower than that in earlier monitoring time(β=-16.28, P<0.01). Conclusion Classroom CO2 concentration level in Hangzhou was closed to that in European schools, while PM2.5 concentration level was much higher. Comparing with other cities in China, classroom PM2.5 and CO2 concentration level in Hangzhou is better. The results highlighted that school location, design and routine management should be advanced consideration for good air quality in classroom.