A method called Rayleigh integral linear superposition algorithm is introduced, in which nonlinear propagation and high order harmonic attenuation are considered. Principle of the method is analyzed. For a concave spherical transducer, medium attenuation and nonlinear propagation in sound focused region are studied. The method is compared with Khokhov-Zabolotskaya-Kuznesov (KZK) method. It is shown that the method is effective in calculating high-intensity focused ultrasound(HIFU) sound fields.