The research on effects of air velocity in heat exchanging pipes on heat storage, temperature and humidity in double-film greenhouse with heat storage system was done during heat saving in winter. The temperature and humidity inlet and outlet of heat exchanging pipes, floor temperature in heat storage greenhouse, air temperature and soil temperature in the adjacent reference greenhouse and outside temperature were measured at different air velocities in the heat exchanging pipes. The experiment results show that the average floor temperature in heat storage greenhouse was respectively 0.8, 1.1, 3.1, 3.9, 4.3 and 5.6℃ higher than that of the soil in the reference greenhouse when the air velocity in heat exchanging pipes was 0.6, 1.0, 1.5, 2.0, 2.5 and 2.8m/s in clear day. While the air velocity in heat exchanging pipes was 0.6～2.8m/s, the air temperature in the heat storage greenhouse was 0.1～0.6℃ lower than that of the reference greenhouse because the hot air temperature was reduced after flowing through the heat exchanging pipes. However the air temperature in heat storage greenhouse was feasible for plant growth during heat saving.