A method for processing privacy data of a block chain by a system comprising a block chain client of a data user side and a block chain node, the method comprising: Acquiring (S101) a data calculation transaction request, wherein the request is initiated by the data user side based on a privacy smart contract, and invocation data in the request refers to data after blinding performed by the data user side, wherein the blinding comprises processing the invocation data according to a rule set by the data user side in a blinding operation; Acquiring (S102) homomorphically encrypted source data according to the request; Invoking (S103) the privacy smart contract according to a calculation task in the request, to perform a calculation for the invocation data and the source data to acquire a calculation result; and Performing (S104) an uplink operation on the request and the calculation result to feed the request and the calculation result back to the data user side, such that the data user side homomorphically decrypts and de-blinds the calculation result to acquire a plaintext calculation result, comprising: requesting, by the data user side, a data provider side of the source data to provide a homomorphic encryption public key; and performing, by the data user side, homomorphic decryption on the calculation result, by using the homomorphic encryption public key, to obtain a preliminary plaintext calculation result; and performing, by the data user side, de-blinding on the preliminary plaintext calculation result based on an inverse operation of the blinding operation performed by the data user side on the invocation data, to obtain a final plaintext calculation result. Acquiring (S101) a data calculation transaction request, wherein the request is initiated by the data user side based on a privacy smart contract, and invocation data in the request refers to data after blinding performed by the data user side, wherein the blinding comprises processing the invocation data according to a rule set by the data user side in a blinding operation; Acquiring (S102) homomorphically encrypted source data according to the request; Invoking (S103) the privacy smart contract according to a calculation task in the request, to perform a calculation for the invocation data and the source data to acquire a calculation result; and Performing (S104) an uplink operation on the request and the calculation result to feed the request and the calculation result back to the data user side, such that the data user side homomorphically decrypts and de-blinds the calculation result to acquire a plaintext calculation result, comprising: requesting, by the data user side, a data provider side of the source data to provide a homomorphic encryption public key; and performing, by the data user side, homomorphic decryption on the calculation result, by using the homomorphic encryption public key, to obtain a preliminary plaintext calculation result; and performing, by the data user side, de-blinding on the preliminary plaintext calculation result based on an inverse operation of the blinding operation performed by the data user side on the invocation data, to obtain a final plaintext calculation result. requesting, by the data user side, a data provider side of the source data to provide a homomorphic encryption public key; and performing, by the data user side, homomorphic decryption on the calculation result, by using the homomorphic encryption public key, to obtain a preliminary plaintext calculation result; and performing, by the data user side, de-blinding on the preliminary plaintext calculation result based on an inverse operation of the blinding operation performed by the data user side on the invocation data, to obtain a final plaintext calculation result. <EOS>