The invention discloses a negative voltage charge pump which comprises a branch circuit which is connected between negative voltage output by a charge pump and first referential voltage, outputs divided voltage as feedback voltage connected to a first input end of a first operational amplifier, and the second input end of the first operational amplifier is grounded. The output end of the first operational amplifier is connected to the grid electrode of a first NMOS tube, and the source electrode of the first NMOS tube. A drain electrode outputs clock control signals. The clock signals are input to a charge pump sequentially through a clock frequency control circuit and a clock amplitude control circuit, and the clock control signals are input to a clock control circuit to adjust the amplitude of clock signals. A second comparator monitors the magnitude of clock control signals. When the clock control signals are greater than first offset voltage, a clock frequency control circuit reduces clock signal frequency, so that the capability of the charge pump matches with the low load current. The circuit stability is improved.