Pump head assembly and emulsion plunger pump

The pump head assembly comprises a pump head body, a hollow cavity is formed in the pump head body, a liquid suction inlet and a liquid discharge outlet are formed in the pump head body, a liquid suction valve assembly and a liquid discharge valve assembly are arranged in the hollow cavity, the liquid suction valve assembly comprises a liquid suction valve port and a liquid suction valve element, and the liquid suction valve port is communicated with the liquid discharge valve element. The liquid discharging valve assembly comprises a liquid discharging valve port and a liquid discharging valve element, the pump head body is provided with a communication port communicated with the hollow cavity, the communication port is used for being communicated with a hydraulic conversion assembly capable of converting mechanical power into hydraulic change in the pump head assembly, and the hollow cavity is provided with a liquid suction channel extending in the horizontal direction. The liquid suction channel extends in