The present invention provides a plastic greenhouse with a triangular top roof for ventilation, comprising: a triangular frame installed in the upper end of a roof of the plastic greenhouse and having a caret shaped front cross section a winding bar installed in both inclined sides of the triangular frame in parallel to the lengthwise direction of the plastic greenhouse a cover fixed in the triangular frame to be wound around the winding bar a motor assembly installed to rotate the winding bar, and enabling the winding bar to be rotated such that the winding bar winds the cover while moving along the inclined side to open the triangular frame, or enabling the winding bar to be rotated backwards such that the winding bar releases the cover while moving along the inclined side in the opposite direction to block the triangular frame and a guide member connected to the motor assembly such that an end is hinged to an installation place, wherein the motor assembly is guided to move together with the winding bar while rotating the winding bar. According to the present invention, an upper part is conveniently moved by minimizing the installation of wires, rings and so on, and the lifespan is lengthened and management is facilitated by preventing foreign materials from being attached onto a water ring pad. Moreover, maintenance and repairs are facilitated by allowing the replacement of a part of vinyl, structural stability is induced by reducing an effect to winds, and heat exchange is quickly performed by placing a vinyl opening/closing section in the upper end.COPYRIGHT KIPO 2016본 발명은 비닐하우스의 지붕 상단에 마련되고, 정단면이 "로 이루어지는 삼각프레임 상기 삼각프레임의 양쪽 경사측에 상기 비닐하우스의 길이방향에 나란하도록 각각 설치되는 와인딩바 상기 삼각프레임에 고정되어 상기 와인딩바 각각에 감겨지는 커버 상기 와인딩바를 회전시키도록 설치되고, 상기 와인딩바가 회전에 의해 상기 커버를 감아서 상기 경사측을 따라 이동함으로써 상기 삼각프레임이 개방되도록 하거나, 역회전에 의해 상기 커버를 풀어서 상기 경사측을 따라 반대방향으로 이동하여 상기 삼각프레임을 차단시키도록 하는 모터어셈블리 및 상기 모터어셈블리에 연결되어 끝단이 설치 장소에 힌지 결합됨으로써 상기 모터어셈블리가 상기 와인딩바를 회전시키면서 상기 와이딩바와 함께 이동하도록 가이드하는 가이드부재를 포함하는 환기용 삼각
