The invention discloses a steel plate for a low-temperature spherical tank container and a heat treatment production method thereof. The steel plate is prepared from less than or equal to 0.12wt% of C, 0.15-0.50wt% of Si, 1.2-1.6wt% of Mn, 0.3-0.8wt% of Ni, less than or equal to 0.010wt% of P, less than or equal to 0.005wt% of S, 0.020-0.045wt% of Al, less than or equal to 0.040wt% of Nb and the balance Fe and unavoidable impurities by melting. The steel plate utilizes low-price carbon and manganese solid solution reinforcement, and through adjustment optimization of a ratio of other elements in the steel plate, good steel plate mechanical properties are ensured under conditions of low carbon equivalent, the steel plate has a good microstructure, good comprehensive performances and welding performances, a cost is reduced and market competitiveness is improved. Through a reasonable heat treatment technology, a uniform ferrite-tempered sorbite microstructure is obtained and impact toughness of a large-thickness steel plate is improved. The steel plate has high purity, impact energy greater than 170J at a temperature of -70 DEG C, an elongation rate of more than 25%, good simulation of performances after welding and welding performances, and good mechanical properties.