An embodiment of the disclosure provides a voice communication method, a calling terminal, a called terminal and a system, the voice communication method includes: establishing, by a calling terminal, a data communication connection between a called terminal and the calling terminal; obtaining a calling terminal international mobile subscriber identity (IMSI), a called terminal IMSI, a first random number for encryption and decryption, and generating a first encryption key; encrypting voice signals according to the first encryption key by using a preset encryption algorithm and obtaining first encrypted voice signals; sending the first encrypted voice signals to the called terminal. The first encryption key is generated according to the calling terminal IMSI, the called terminal IMSI, and the voice signals are encrypted by using the preset encryption algorithm, thus an encryption process is highly targeted and highly confidential, and security of voice services is improved.