Abstract: Voltage-frequency-conversion, as a signal processing and transformation technology, is widely used in every field.In this paper, structure design and working principle of a new and low-cost voltage-frequency-conversion circuit based on 555 timer is discussed in detail.Moreover, simulation results based on Multisim soft show that the circuit designed in this paper is of its stability, linearity and correctness in voltage-frequency transformation.The converting precision of the proposed circuit achieves 99.524, with error of 0.476.