The present invention relates to a heat insulation apparatus for a plastic greenhouse, which comprises first guide pipes installed on both sides to have a slope to put an opening/closing area of the ceiling of the plastic greenhouse in the middle； second guide pipes to have a slope to be separated upward from the first guide pipes in parallel； a first winding assembly having first carriers installed along each first guide pipe to be movable, first motors installed in the first carriers, and a first winding bar between the first carriers to rotate by the first motors； a second winding assembly having second carriers installed along each second guide pipe to be movable, second motors installed in the second carriers, and a second winding bar between the second carriers to rotate by the second motors； a plastic sheet fixed to the upper end of the first guide pipes and fixed to the first winding bar on the terminal end； a heat insulating curtain fixed to the upper end of the second guide pipes and fixed to the second winding bar on the terminal end； a first wire installed on the winding path of the plastic sheet and supporting the plastic sheet； and a second wire installed on the winding path of the heat insulation curtain and supporting the heat insulation curtain. According to the present invention, the heat insulation apparatus for a plastic greenhouse has an excellent heat insulation effect due to a multi-stage heat insulation method, is easy to open/close and excellent in the reliability of the opening/closing operation, is able to be stably constructed on a large-sized plastic greenhouse as well as a small-sized plastic greenhouse, and facilitates construction and demolition.본 발명은 비닐하우스의 천장에 개폐 영역을 사이에 두고 양측에 경사지게 각각 설치되는 제 1 가이드파이프； 제 1 가이드파이프로부터 상방으로 이격되어 나란하도록 경사지게 각각 설치되는 제 2 가이드파이프； 제 1 가이드파이프 각각을 따라 제 1 대차가 이동 가능하게 설치되고, 제 1 대차에 제 1 모터가 설치되며, 제 1 모터에 의해 회전하도록 제 1 대차 사이에 제 1 와인딩바가 설치되는 제 1 와인딩어셈블리； 제 2 가이드파이프 각각을 따라 제 2 대차가 이동 가능하게 설치되고, 제 2 대차에 제 2 모터가 설치되며,
