The invention discloses an online self-calibration dual-mode differential resonant gyroscope system. The system simultaneously drives a first mode and a second mode in a force balance mode, and simultaneously detects the first mode and the second mode, so that resonant gyroscopes in two force balance modes are realized on the same gyroscope structure, and the interference of rigidity quadrature errors and damping quadrature errors can be completely inhibited through dual-mode difference. Complete physical means are adopted to mathematically eliminate the rigidity quadrature error and the damping quadrature error, the defect that only the rigidity quadrature error can be suppressed by using a circuit means in a force balance mode is avoided, the complexity of a control circuit is simplified, and online self-calibration of the zero error of the resonant gyroscope can be realized.