In current satellite management, each satellite is usually equipped with a special system, and the satellite operation task scheduling and the tracking task scheduling are often separately conducted. This paper analyzes the characteristics of resource occupancy in satellite task scheduling and establishes a unified constraint satisfaction model, which takes satellite onboard independent events and satellite downlink events as scheduling objects, and event executable opportunities as key scheduling resources. With this model, the traditional satellite operation task scheduling and tracking task scheduling are integrated into a unified modeling method. To ensure the generality and adaptability of the model, a multi-strategy collaborative solving framework with heuristic construction, intelligent optimization and specific algorithm improvement is formulated, contributing to a loosely coupled and modular architecture of the satellite task scheduling algorithm and model. Experiment results show that the proposed method can make up for the limitations of traditional models in agile remote sensing satellite scheduling and tracking scheduling of different orbiting satellites, and it has good applicability and optimization effects on Benchmark and practical problems.