Gravel-mulched land was the unique and conventional farming system and its planting area was enlarged year by year in arid region of northwest China. The planting area of watermelon in gravel-mulched land reached more than 33% of total area of gravel-mulched land. But the stresses of lower temperature in early spring and water shortage during growth period of watermelon were major limiting factors for watermelon yield increasing in gravel-mulched land. To find the ways improving soil temperature in early spring and water use efficiency(WUE), field trials of different plastic film mulches, with full plastic film mulch (FM), soil bed-forming and much plastic film for collecting rainfall (RM), half soil plastic film mulch (HM) and no plastic film mulch(CK),were conducted in gravel-mulched land in arid region of Gansu to study the effects of soil temperature, soil water and growth as well as yield and quality of watermelon. The results indicated that the daily soil temperature in 0-25cm soil layer changed as "S" and transferred from soil surface layers to deeper layers, the time of maximum and minimum soil temperature appearance delayed 1h as soil depth deepened 5cm.The changes of soil temperature in 5cm soil layer were greater than other soil layers and its changing degree was decreased as soil layers deepened. Soil temperature increasing in 0-25cm soil layer followed as FM>RM>HM>CK and the daily average soil temperature of FM, RM and HM treatments increased by 2.8℃、2.0℃ and 1.8℃, compared to CK, respectively. The effects of soil temperature increasing in early growing stage were more obvious, it increased by 3.29℃,2.53℃ and 2.04℃ in seedling stage but 1.72℃,1.36℃ and 1.26℃ in fruit stage for FM, RM and HM treatments compared to CK, respectively. FM and RM treatments were the key plastic film mulches influencing soil water. The effects of rainfall collection were obvious for RM treatments as its bed forming from sowing to seedling stage and the effects of soil water conservation were significant for FM treatments after extending stage as soil water evaporation decreasing. Compared to CK, the average soil water content for FM and RM treatments increased 1.1 and 2.2 percentage points from sowing to seedling stage and 2.2 and 2.2 percentage points in extending stage, respectively. The watermelon growth was rapid up after mulching plastic film. Compared to CK, the length of main vines were increased by 12.7%,11.5% and 8.8% and leaf area index were increased by 67.8%,31.4% and 25.6% for FM,RM and HM treatments in fruit stage, respectively. The chlorophyll content of leaf reached highest value in vines stage and increased by 14.1%,13.7% and 12.2% for FM,RM and HM treatments compared to CK, respectively. The watermelon yield was increased under plastic film mulches, it increased by 145.81%、99.32% and 95.46% for FM, RM and HM treatments compared to CK, respectively. The content of soluble solid and soluble sugar changed as FM>RM>HM>CK. Compared to CK, the content of soluble solid increased by 11.64%,7.90% and 2.70% in the centre of watermelon fruit and 13.68%,8.57% and 4.22% in the side of watermelon fruit, also the content of soluble sugar increased by 15.77%,9.16% and 4.72% for FM,RM and HM treatments, respectively. But the content of Vc, fiber and effective acid were influenced slightly by plastic film mulches. By analysis comprehensively FM and RM treatments were optimum mulching options in gravel mulched land.