1. A method for obtaining clear images through the rain, snow or fog, wherein, the method comprising the steps of: (A), a digital signal processor (DSP) processing module controls a laser pulse generating module to output laser pulse signals with a default pulse width, and shuts the laser pulse generating module down when a first default time arrives; (B), when the laser pulse generating module is outputting the laser pulse signals, the DSP processing module controls an electronic shutter of an image pick-up device open after delaying for a second default time period, and shuts down 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; and (C), processing video images captured by the image pick-up device through a field-programmable gate array (FPGA) module, so as to make output images clearer, or make a capturing distance farther but obtain clear images.