The utility model discloses a guide rail support used for photovoltaic assembly construction, comprising a support pedestal assembly which comprises a pedestal, a connecting rod and a fixing rod; thesupporting assembly comprises a triangular frame, a supporting rod and a guide rail; the sliding assembly comprises a fixing block, a fixing groove and a sliding block, the fixing groove is formed inthe upper surface of the fixing block, and the sliding block is fixedly connected to the bottom of the fixing block; the fixing assembly comprises a supporting block, a threaded sleeve, a threaded rod, a rotary knob, a bottom plate and a cone. According to the utility model, the threaded rod rotates in the threaded sleeve; adjusting height, a bottom plate is arranged at the bottom end of the threaded rod; the cone is arranged at the bottom of the bottom plate, the threaded rod drives the cone to rotate and move downwards, when the guide rail is fixed, only the knob needs to be rotated, the knob drives the threaded rod to rotate, then the threaded rod drives the cone below the bottom plate to rotate, the cone is screwed into the ground to support the base, and therefore the support guide rail is prevented from shaking in the installation process.