In accordance with the working environment and loading features of the balance displayed in the airdrop test, the design load and the balance structure are defined. Safety factor of the spring is calculated in the every extreme overloading condition specific to the practical use of the balance. Stress field of the balance is deduced through finite element analysis, and the stress distribution of the whole balance is obtained. The results are tested further, which offer theoretic support for the final structure design of the balance.