In order to improve the employment rate of students, this study has built a blockchain based big data platform for student employment, and built an exchange environment for mutual trust among enterprises, universities and students. By analyzing the employment status and problems of college graduates in China, and combining the characteristics of blockchain, a big data platform for student employment based on blockchain alliance is established. After that, it describes the operation process of the platform and analyzes the advantages of the platform. The final results show that if blockchain technology can be applied to student employment, it can not only alleviate the employment problem of Chinese college students, but also reasonably adjust human resources, which is conducive to social harmony and stability.