A method for backing up a private key of a second electronic signature token, comprising: obtaining by each of a first electronic signature token and the second electronic signature token a first matching code; negotiating, by the first electronic signature token and the second electronic signature token, an encrypting strategy and a decrypting strategy corresponding to the encrypting strategy used for communication between the first electronic signature token and the second electronic signature token using the first matching code; encrypting by the first electronic signature token a private key backup request data packet using the encrypting strategy, wherein the private key backup request data packet comprises matching code information; sending by the first electronic signature token an encrypted private key backup request data packet; decrypting by the second electronic signature token the encrypted private key backup request data packet to obtain the private key backup request data packet, after receiving the encrypted private key backup request data packet; obtaining by the second electronic signature token a second matching code from the matching code information in the private key backup request data packet, and taking the second matching code as a first pending verification code; if the first pending verification code is identical with the first matching code obtained locally, encrypting by the second electronic signature token a private key backup response data packet using the encrypting strategy, wherein the private key backup response data packet comprises the private key; sending by the second electronic signature token an encrypted private key backup response data packet; and decrypting by the first electronic signature token the encrypted private key backup response data packet using the decrypting strategy to obtain the private key backup response data packet after obtaining the encrypted private key backup response data packet, and obtaining the private key from the private key backup response data packet. obtaining by each of a first electronic signature token and the second electronic signature token a first matching code; negotiating, by the first electronic signature token and the second electronic signature token, an encrypting strategy and a decrypting strategy corresponding to the encrypting strategy used for communication between the first electronic signature token and the second electronic signature token using the first matching code; encrypting by the first electronic signature token a private key backup request data packet using the encrypting strategy, wherein the private key backup request data packet comprises matching code information; sending by the first electronic signature token an encrypted private key backup request data packet; decrypting by the second electronic signature token the encrypted private key backup request data packet to obtain the private key backup request data packet, after receiving the encrypted private key backup request data packet; obtaining by the second electronic signature token a second matching code from the matching code information in the private key backup request data packet, and taking the second matching code as a first pending verification code; if the first pending verification code is identical with the first matching code obtained locally, encrypting by the second electronic signature token a private key backup response data packet using the encrypting strategy, wherein the private key backup response data packet comprises the private key; sending by the second electronic signature token an encrypted private key backup response data packet; and decrypting by the first electronic signature token the encrypted private key backup response data packet using the decrypting strategy to obtain the private key backup response data packet after obtaining the encrypted private key backup response data packet, and obtaining the private key from the private key backup response data packet.