The invention provides a portable harmonic detector and a harmonic analysis method. The harmonic detector is composed of a parameter sampling circuit, a data processing circuit, a communication circuit and a power supply circuit. The parameter sampling circuit and the power supply circuit combine the electrical parameter sampling of an instrument and a power supply part of the device into one body, and realize power supply to the device while acquiring voltage and current parameters. The data processing circuit uses a single-chip microcomputer and a peripheral circuit thereof to realize data acquisition and performs data interaction and storage with an electric energy quality acquisition chip so as to realize parameter acquisition and calculation. The electric energy quality acquisition chip part uses an existing chip specially used for electric energy quality acquisition to carry out harmonic analysis. The communication circuit is composed of an RS485 interface circuit and a WiFi circuit. The harmonic analysis method comprises three parts of harmonic data classification, harmonic data calculation and harmonic data analysis. According to the harmonic detector, the cost of the device is greatly reduced, the overall size of the device is reduced, and the detector is convenient for inspectors to use.