<p indent="0mm">Most of the existing quantum secure multiparty multiplications use entangled states to carry secret information. However, the preparation of these quantum states is difficult. In order to solve this problem, a single-particle secure multiparty product protocol based on a <italic>d</italic>-level Lagrange unitary operator is proposed. In this protocol, a semi-honest third party (Server) and each participant share a private key. The participant first uses the private key and random number to multiply his own secret integer with module <italic>d</italic>, and then he uses Lagrange unitary operator to encode the calculation result into an unbiased basis particle. The server obtains the encoded information by measuring the particle sent back by each participant. Finally, the server uses the module <italic>d</italic> product of all the random numbers sent by the participant’s representative to calculate the product corresponding to the secret integers of multiple participants. Performance analysis shows that, compared with similar protocols, the proposed protocol requires less of the entity’s quantum computing capabilities. In terms of security, this protocol can resist both external and internal attacks. Finally, the proposed protocol uses the <italic>Q</italic># quantum programming language combined with Python language to simulate and verify its correctness.