The portable LNG sampler is a special product developed based on the characteristics of LNG. It is mainly used by third-party testing agencies to sample from LNG dosing machines. The product is small, lightweight and easy to carry, with adjustable temperature and pressure and high reliability. The liquefied natural gas is connected from the liquid filling machine to the quick connector (liquid filling port) of the mobile LNG sampler through the liquid filling gun assembly, and then passes through the cryogenic stop valve, and the sampling system is opened and closed through the stop valve. After passing through the cryogenic stop valve, it enters the check valve, enters the electrically heated pressure-regulating vaporizer, and after being heated and pressurized, enters the buffer tank. The buffer tank can evenly mix the sample gas and stabilize the system flow. After passing through the buffer tank, it is connected to the one-way valve. The function of the one-way valve is to prevent subsequent system failures and other media from entering the system. Following the one-way valve, the system is divided into a safety valve pipeline and a hose injection pipeline. The safety valve pipeline is used to prevent system pressure from being released in time when the pressure regulating valve fails to protect system safety. The hose sampling pipeline is connected to the sampling cylinder through a quick connector to complete the natural gas sampling work.