According to the characteristics of solar radiation and the energy equation and heat transfer characteristics of flat-plate heat collector, the influence of its installation tilt and orientation on performance of the collector was investigated. The transient simulation software of solar energy was used to perform annual simulation and analysis of the parameters such as outlet water temperature of and solar radiation on fiat-plate heat collector in Lanzhou area, which was fixed with 25°, 45° and 90° installation tilt and southward or eastward orientation, respectively. Result shows that in summer, the eastward collector with 45° installation tilt can better absorb solar radiation, and its outlet water temperature will be the highest, while southward one with 90° installation tilt will be the worst. In contrast to this, in winter, the east ward one with 90° installation tilt and southward one with 90° installation tilt will be the worst and the best, respectively. Collector outlet temperature will increase with the irradiance projected on the collector, but it will be not simply linear, exhibiting some fluctuation due to many influencing factors.