The utility model provides a light explodes downthehole bilinearity of fixing a position and gathers ability demolition unit, through set up push device can with the double -line type gather can the pencil propelling movement to light explode downtheholely to rotatable regulation double -line type gather can the pencil make the double -line type gather can the groove the central line explode hole center line and the coincidence of tunnel outline line with light, release is concentrated along the direction of tunnel outline line to the energy that explosion produced, forms the tunnel profile face that levels the rule after the blasting. Downthehole central positioner structure is improved, reduce its area of contact and bilinearity of exploding the hole with light and gather can the demolition unit phototropic downthehole propulsive resistance that explodes, realize gathering can demolition unit smooth dress hole operation, both satisfied the needs of production and design, can reduce explosion again and to the destruction of rock mass on every side, reduce rock drift support cost.