The invention provides a high-performance phase-controlled circuit breaker fundamental-wave detection device. The device is formed by sequential electrical connection of a voltage transformer, a signal conditioner, an analog-to-digital converter, a modulation integration observe, and a digital-to-analog converter. Firstly, the voltage transformer is adopted to convert a power grid voltage signal,and the high-voltage signal is converted into a low-voltage signal; then the low-voltage signal further converted into a digital signal for detection through the signal conditioner and the analog-to-digital converter, and the digital signal is sent to the modulation integration observer; and finally, a fundamental digital signal of power grid voltage is converted into analog quantity through the digital-to-analog conversion circuit. This device can realize accurate extraction on a fundamental wave of the power grid voltage under severe working conditions that the power grid voltage is rich innoise and odd harmonics, and fundamental-wave frequency of the power grid voltage changes, a structure thereof is simple, anti-interference ability is high, detection accuracy is high, signal delay issmall, and improvement of overall performance of a phase-controlled circuit breaker is facilitated.