Many noise source identification measures show that the source of the abnormal noise of an idling truck is the air compressors induction noise. Based on this, the expansion muffler and interference muffler are designed on the inlet duct of the air compressor. The acoustic finite analysis for the inlet system including muffler, air cleaner and the inlet duct of the air compressor and the engine shows that the muffler has remarkable transmission loss. Base on these, the samples for the expansion muffler and the interference muffler are made and tested in the truck for verifying noise control effect. Result shows that the designed muffler can control the noise effectively and the interference muffler is better than the expansion one. Considering the shortage of the designed interference muffler and the characteristic that the air compressor shares the same inlet system with the engine, an engineering design for the interference muffler is present. The acoustic transmission loss and the noise control of the engineering one are also notable. Although the engineering interference muffler is a litter worse than the interference one, it avoids the shortage of the interference one that the duct is too long to choking. Lastly, an intake time testing for the gas storage is done with the engineering interference muffler, though the intake time is a bit longer, it is still better than the national standard.