The invention discloses a pulse density modulation method and a pulse density value signal conversion circuit. The method comprises the following steps of (S01) obtaining bits n of a binary density value, setting the bits of a counter to be n and setting an initial value of the counter to be 0 or 1; (S02) searching the rightmost 1, obtaining the bits j of the count of the rightmost 1 of a current value i of the counter from right to left, wherein the number in the counter is a binary number and the minimum value of j is 1; (S03) judging whether the corresponding bit is equal or not, if the jth bit of the d from left to right is 1, the signal bit output in the period is, if the jth bit of the d from left to right is 0, the signal bit output in the period is 0; and (S04) adding 1 to the value i of the counter, entering the next period and skipping to the step (S02). Output voltage can be more even and smooth.