The present invention discloses a method and image pick-up system for obtaining clear images through the rain, snow or fog. The method includes a DSP processing module controls a laser pulse generating module output laser pulse signals with a default pulse width, and shut the laser pulse generating module down when a first default time arrives; when the laser pulse signals is being output, the DSP processing module controls an electronic shutter of an image pick-up device open after delaying for a second default time, and close the electronic shutter when a third default time arrives; wherein, the third default time is a lasting period of the default pulse width of the laser pulse signals; then, an FPGA module processes the images captured by the image pick-up device, and outputs clearer images, or makes the capturing distance farther but obtains clear images.