Ammonia fuel engine and power generation system driven by ammonia fuel engine

An ammonia fuel engine comprises an ammonia gas tank, a shell, a power unit and an ammonia-hydrogen conversion unit. The ammonia gas tank is provided with a tank body and liquid ammonia arranged in the tank body; the shell is provided with a setting hole for inserting the ammonia gas tank; the power unit is arranged in the shell and comprises a gas engine and a first gas storage tank which is respectively communicated with the gas engine and the setting hole, and the first gas storage tank is provided with a regulating valve corresponding to the ammonia gas tank; the ammonia-hydrogen conversion unit is arranged in the first gas storage tank, and is provided with a heat exchanger for ammonia gas to flow through, a catalyst for converting the ammonia gas into hydrogen, and a filter for filtering the hydrogen; when liquid ammonia enters the first gas storage tank, the liquid ammonia is reduced into ammonia gas through pressure relief of the regulating valve, is heated by the heat exchanger to reach the working t