The invention discloses an error data injection attack defense method based on hybrid homomorphic encryption. The method includes: firstly, constructing an attack vector, obtaining the influence of asystem state estimation result, then obtaining an object needing encryption protection, rewriting the static Kalman filtering state estimation algorithm iteration process, and obtaining an iteration form supporting the hybrid homomorphic encryption process; designing a quantization and mapping method from a real number field to a plaintext space to adapt to homomorphic encryption operation, and respectively designing and executing communication protocols of an addition homomorphic algorithm and a multiplication homomorphic algorithm; and finally, defining different groups participating in thestate estimation algorithm, designing calculation tasks required to be executed by the different groups, and further designing an encryption state estimation protocol for ensuring complete confidentiality of data in calculation and communication processes. The protocol overcomes the problem that the reliability and accuracy of calculation results from a plaintext domain to a ciphertext domain aredifficult to guarantee, considers the requirements of participants for data confidentiality, and can effectively resist wrong data injection attacks in an information physical system.