The invention relates to a low-power consumption and accurate sleep timer circuit. The low-power consumption and accurate sleep timer includes a high-frequency clock source, a low-frequency clock source, a clock state indicating circuit, a control circuit, timers, a high-frequency timing margin calculator, a low-frequency timing margin calculator, comparators and a timer result decision device. According to a low-power consumption and accurate sleep timing method, sleep timing is completed by means of automatic switching of two timers. According to the circuit of the invention, circuit structures such as the high-frequency clock source, the low-frequency clock source, the clock state indicating circuit, the control circuit, the high-frequency timing margin calculator and the low-frequency timing margin calculator are adopted; and according to the method, hardware is utilized to control the high-frequency timing margin calculator and the low-frequency timing margin calculator. With the circuit and method adopted, a detect that switching is carried out by means of a processor in the prior art can be eliminated, the resource overhead of the processor can be decreased, timing accuracy can be improved, and power consumption of a system can be decreased.