The new petroleum coke slurry fuel system was adopted in a R180 diesel engine, and an investigation was carried out in the modified diesel engine with fuel of petroleum coke slurry. The speed, torque, specific fuel consumption, exhaust gas temperature, and HC, CO, NOx , smoke emission concentrations of the engine with fuel of petroleum coke slurry were measured respectively, and the comparison to the engine with fuel of No.0 diesel fuel was made. The results show that under the conditions of 1200, 1600, 1800 r/min and burning petroleum coke slurry, engine maximum power is reduced by about 6.2%, 19% and 21% respectively compared with burning diesel fuel, and the average exhaust gas temperature increases by about 5.3%, 19.1% and 34.2% respectively; the HC emissions reduced at 1200 r/min, and are similar to the diesel fuel at 1600, 1800r/min; the CO emissions are close to diesel fuel; the NOx emissions decreased; the exhaust smoke density is similar to diesel fuel at 1200 r/min , and is higher than diesel fuel at 1600, 1800 r/min.