A heat transfer characteristic analysis method for a heat pipe in a nuclear power system mainly comprises the following steps that 1, inputting a heat source of the heat pipe, the working condition of a heat trap, a working medium, a structure and geometric parameters, and setting calculation time; 2, dividing the heat pipe into control bodies and carrying out initialized calculation; 3, calculating the change rate of the temperature of the pipe wall control body along with time, and considering the axial heat transfer and boundary conditions of the heat pipe; 4, calculating the change rate of the temperature of the control body in the wick along with time, ignoring convective heat transfer caused by liquid flow, and regarding the change rate as pure heat conduction; 5, calculating the change rate of the temperature of the control body in the steam cavity along with time, and simplifying continuous steam flowing into thermal resistance heat conduction; 6, solving the equation set by using a Gear algorithm, and completing calculation of all time points; 7, checking the heat transfer limit of the heat pipe and calculating equivalent thermal resistance; 8, comparing and analyzing the influence of the heat pipe key parameters on the heat transfer performance. Transient calculation and heat transfer characteristic analysis are carried out on different heat pipes, and suggestions and guidance are provided for design of a high-performance heat pipe heat exchanger in a nuclear power system.