Through pot experiment, dynamic changes of temperature and humity in micro-environment at growth period of pakechoi, and water consumption rules of crop transpiration and planting substrate evaporation were studied under different coverage degrees. The results showed that the air temperature and humidity increased with the coverage degrees increasing at growth point. During day and night, evapotranspiration decreased with increasing of coverage degrees. The variation of daytime evapotranspiration was significant, the order of evapotranspiration was the no-coverage treatment >1/2 coverage treatment >15/16 circle coverage. The total water consumptions tended to decrease with coverage degrees increasing during pakchoi growth period. Water consumption of 1/2 circle coverage, 3/4 circle coverage, and 15/16 circle coverage were 91.34%, 69.03% and 40.74% of the none coverage treatment, respectively. To none coverage, 1/2 circle coverage, 3/4 circle, and 15/16 circle, and their corresponding average dry weights of the aerial parts were 5.551, 6.536, 5.143, 3.345 g, and their corresponding water use efficiency were 1.53, 1.97, 2.05, 2.25 kg/m3. The above results indicated that the water use efficiency of pakchoi increased with the increasing of coverage degrees, the maximum value of water use effiieny appeared at 15/16 circle coverage treatment.