The utility model discloses a fuel filter. The fuel filter comprises a filter seat, wherein a rough filtration oil inlet channel, a rough filtration oil outlet channel, a fine filtration oil inlet channel and a fine filtration oil outlet channel are arranged in the filter seat; a filter cover and a rough filter shell are mounted on the filter seat in a detachable way; the filter cover and the filter seat form a fine filtration cavity; the rough filter shell and the filter seat form a rough filtration cavity; a rough filtration element is mounted in the rough filtration cavity; a rough filtration oil inlet cavity is formed in the exterior of the rough filtration element; a rough filtration oil outlet cavity is formed in the interior of the rough filtration element; the fine filtration oil inlet channel is communicated with a fine filtration oil inlet cavity; an oil outlet of a fine filtration element is communicated with the fine filtration oil outlet channel; an oil outlet of the rough filtration element is communicated with the rough filtration oil outlet channel; the rough filtration oil inlet channel is communicated with the rough filtration oil inlet cavity. The inside of the rough filtration cavity and the inside of the fine filtration cavity are separated, the outside of the rough filtration cavity and the outside of the fine filtration cavity are connected, double-grade filtration is realized, the requirement of a common rail system is met, a diesel engine does not need using two independent filters, the filter is more compact, and the installation space of an internal combustion engine is saved.