The invention discloses a power reactor adopting a uranium zirconium hydride fuel element. According to the power reactor, the fuel assembly adopted by the reactor core is the square assembly or the hexagonal assembly; a high uranium loading uranium zirconium hydride fuel thin rod element is adopted; dispersed erbium is adopted as the flammable poison, and the erbium poisons with different contents can be arranged in regions in the assembly and the reactor core; the negative reactivity temperature coefficient of the reactor core fuel is -5 to -10 pcm/K, and the life period of the reactor core is more than 1000 EFPD. According to the present invention, the reactor core arrangement can meet requirements of stuck rod criteria, long burn-up life period and flattening reactor core power distribution; the reactivity of the poison burning-up release is matched with the reactivity of the fuel burning-up loss; the reactor core of the uranium zirconium hydride power reactor of the present invention has characteristics of inherent safety and long life period, and is suitable for marine power, low-temperature heating reactor, moveable vehicle nuclear power, bathyscaphe power and other uses.