Disclosed is cross-linking agent modified polyethylene geogrid. Components with percentage content of the cross-linking agent modified polyethylene geogrid are 65% to 70% of high-density polyethylene (HDPE), 21% to 26% linear low density polyethylene (LLDPE), 0.5 % to 1% of dicumyl peroxide (DCP), 0.5% to 2% A-151, 0.5% to 1% dibutyltion dilautate (DBTDL) and 4.5% to 5% color master with carbon black content more than 45 %. The manufacturing method of the cross-linking agent modified polyethylene geogrid comprises steps as below: 1) master batch manufacturing: mixing part of HDPE, LLDPE, DCP, A-151 and DBTDL together, enabling the blend to pass through a screw extruder to be fused at the temperature of 160 DEG C to 200 DEG C to manufacture the master batch in a melting mode; 2) mixing of the master batch, the color master and remaining HDPE; 3) molding of sheet materials; 4) punching; 5) stretching. The cross-linking agent modified polyethylene geogrid improves toughness, significantly relieves the phenomenon of rib portion brittle fractures, and effectively lowers cost. Stretching length of a single rib is increased by 10 % to 20 %, strength is improved by 5 % to 10 %, and gram weight of a product is reduced by 20 % to 30 %.