Designs a temperature measurement system based on FPGA and LM75A. The design of hardware uses EP4CE15F17C8N as the main controlling chip, and applies the digital temperature sensor LM75A to test the environment temperature and the LM75A own IIC bus interface to transmit data, displaying the temperature via the Digital tube in real time. The software design, using the idea of top-down modular design thought, first, designs a IIC communication module and a temperature display module, and then, programs the top-level module and makes the modules integration. The practice results show that the system is precision in measuring temperature and operates stably.