The utility model provides a four sword skull trephines belongs to the gimlet field, contains integral type drill bit, drilling rod and drillstock, the drill bit contains four cutting edges, and wherein two are the main cutting edge, the main cutting edge be that central symmetry distributes and the main -edge point on drill bit excircle circumference, draw a sword and be central symmetry and distribute and draw the blade tip on the excircle circumference of drill bit for drawing a sword for other two, the main cutting edge with draw that a sword distributes alternately and the sword body is in a spiral arrangement, be provided with slot, two total slots within a definite time at main cutting edge and adjacent stroke of sword simultaneously, the drilling rod contains four chip grooves, two chip grooves of giving first place to wherein, main chip groove is corresponding with the position of main cutting edge, other two it is corresponding with the position of slot to assist the chip groove in order to assist the chip groove, main chip groove with assist the chip groove and distribute alternately and be in a spiral arrangement on the drilling rod, drawing the blade tip and than the high 0.5mm of main -edge point, adding man -hour, draw sword elder generation cutting -up circle, the main cutting edge bores and digs the pore -forming, and 2 subsidiary chip grooves make the chip removal more smooth and easy, have reduced the friction of sweeps with the pore wall, make the difficult burn of cutting edge, make high, the surperficial smoothness in hole of processing hole size precision, and the tool life is high to improve the chasing speed, productivity gain.