Abstract: In order to improve the utilization rate of light energy with agricultural plastic film, 2-octyl-1, 3-diphenyl-1, 3-propandione and its Sm complexes (C1) were synthesized by phase transfer catalysis.C1 was characterized by IR, EA and ¹H NMR.The compatibility between C1 and polyethylene (PE) and the effects of PE film containing C1 on the photosynthesis of some Virginia tobacco cultivars, such as K326、RG11 and GB-1, were tested.The results showed that:1) C1 and PE showed relatively good compatibility while adding a long carbon chain compound;2) C1 excitated by light of 391nm could emit 650nm light which was in the vicinity of the wavelengths, 643nm and 660nm, needed by plant photosynthesis;and 3) the photosynthetic rate of tobacco plant was improved as the chlorophyll synthesis in tobacco leaf was promoted by agricultural PE film incorporated with a right amount of C1.