The pour point depressant for diesel was prepared by firstly making modifacation of C5 petroleum resin with maleic anhydride, and then modified with octadecanol. Four factors were studied on the influence of freezing point and cold filter plugging point, which are, respectively, the amount of maleic anhydride and initiator, the time of reaction, the temperature of reaction. The result shows that, the best depression capacity of pour point depressant for diesel is acquired with the amount of maleic anhydride is 15%，and the amount of the initiator is 1.0%, and the temperature is 180 ℃ and the time is 3.0 h.

The process of oxidation reactions and solvent extraction for coking diesel with hydrogen peroxide as an oxidant and methanol as the extractant was studied. The influences of the oxidants amount, reaction time, oxidation temperature, the ratio of oxidants to catalyst, the ratio of oil to extraction agent were investigated. The optimal operation conditions are as follows: reaction temperature 60 ℃，oxidation time 60 min，volume ratio of oxidants to diesel 0.1，formic acid as a catalyst，volume ratio of oxidants to catalyst 1.0; volume ratio of extraction to oil 1.0，extracting at room temperature for 20 min. The results show that the yield of diesel fuel is 93.0%，and the sulfur content of diesel can be reduced to less than 350 μg/g.

The catalytic oxidation experiments were carried out to prepare the horniness oxidized wax from paraffin wax and polyethylene. The results show that good products can be obtained under the following conditions: reaction temperature 170 ℃, reaction time 7 h, mass ratio of paraffin wax and polyethylene 7∶3, the amount of catalyst 0.01%, the amount of additive 1.0%, the air flow 0.20 m3/h. acid number of the product was 9.82 mg(KOH)/g, saponification number is 79.19 mg(KOH)/g, penetration is 9.2 (0.1 mm), melting point was 87.4 ℃, index of refraction(75 ℃ ) was 1.453 6. As compared with natural hard wax(carnauba wax)，their properties were quite similar each other.