A current sample-and-hold circuit and a sensor, are provided. The current sample-and-hold circuit is used for offsetting a background photocurrent of a photodiode, and includes a capacitor and a first transconductance amplifier which has adjustable transconductance and outputs a sampled current to the photodiode to offset the background photocurrent of the photodiode. One end of the capacitor is connected with a power supply, the other end of the capacitor is connected with one end of the first transconductance amplifier; and the other end of the first transconductance amplifier is connected with the photodiode to output the sampled current to the photodiode. When the background photocurrent of the photodiode is increased, a change of a voltage of the capacitor within a large range can be avoided by increasing the transconductance of the first transconductance amplifier, so that the current sample-and-hold circuit can offset a larger background photocurrent.