The present invention relates to a plastic sheet fixture for plastic greenhouses for strainedly fixing a plastic sheet to cover a framework including a pipe or the like, and more specifically, to a plastic sheet fixture for plastic greenhouses which easily fixes a plastic sheet, has no problem of the plastic sheet tearing while fixing, and has no risk of pollution by rust generated by the corroded fixture even upon use for a long time. Thus, the present invention relates to a plastic sheet fixture for plastic greenhouses which includes: an elastic stand having an upper part narrower than a lower part, and provided at both sides of a flat plate-type base; and a fixing spring having a side cross-sectional surface provided with an engaging part at both sides of a mountain-shaped elastic unit, to be accommodated in a storing area of a body having a side cross-sectional surface provided with detachment preventing members facing each other at upper ends of the elastic stand. The fixing spring further includes, in an upper part thereof, a pressing member which is made of rubber, is accommodated in the storing area, and has a narrow width to press the fixing spring; the width of the fixing spring is set to be equal to or less than a distance from the intersection between the base of the body and the elastic stand to the detachment prevention member on the opposite side to allow the fixing spring to be easily accommodated in the storing area; and the pressing member has a structure in which electric members are horizontally symmetrically formed under a rope support member protruding outwardly from the body such that the electric members contact the elastic unit of the fixing spring and a horizontal ground plane contacting the engaging member is provided in the form of ″ㅅ″ in the elastic member.본 발명은 파이프 등으로 이루어지는 골조의 외부에 비닐을 씌울 때 비닐을 긴장상태로 고정할 수 있도록 하는 비닐하우스용 비닐고정구에 관한 것으로서, 비닐을 간편하게 고정할 수 있도록 함과 아울러 고정하는 과정에서 비닐이 찢어지는 문제점이 없으며 장시간 사용 시에도 고정구가 부식되어 녹물이 비닐을 오손하게 되