The invention discloses a water stop construction method for a tunnel anchor rod passing through a waterproof plate, comprising the following steps: 1) mounting a water stop tray: forming a concrete spraying surface on the surface of a surrounding rock surface after tunnel initial spraying is completed, sleeving the water stop tray on an exposed anchor rod, and enabling the water stop tray to be clung to the concrete spraying surface; 2) laying a hot melting pad: laying a hot melting pad on the concrete spraying surface on the outer side of the water stop tray; (3) arranging a waterproof plate: enabling a primary support exposed anchor rod to penetrate through a waterproof plate, attaching the waterproof plate to the water stop tray, fixing the waterproof plate and the water stop tray in abonding manner, and connecting the waterproof plate and the concrete spraying surface in a hot melting manner through a hot melting pad; and 4) packing asphalt between the anchor rod and the water stop tray: filling an asphalt filling area in the gap between the water stop tray and the exposed anchor rod with asphalt. In the tunnel construction process, a sealed waterproof structure can be formedat the weak part, penetrating through the waterproof plate, of the primary support exposed anchor rod, so that the lining resistance is effectively improved.