In order to further improve the pavement performance of Novachip ultra-thin wearing layer, the direct injection environmental protection modifier is applied in it. The effects of direct injection modifiers with the different dosages on the high-temperature performance, water stability and low-temperature cracking resistance of the mixture are analyzed. The results show that compared with SBS modified asphalt, the high temperature stability of mixture is improved by 118% and its freezing-thawing splitting strength ratio is improved by 14.3% when the dosage of the direct injection modifier is 0.8% of the ore mass, but the low-temperature cracking resistance does not meet the requirements of the specification. Therefore, the optimal dosage is 0.6% of the ore mass. Through the paving verification of test section, the direct casting modified asphalt mixture is constructed more conveniently and the pavement performances are more excellent. Its each performance can meet the current code requirements.