The work aims to investigate the anticorrosion properties and film formation properties of cyclohexyl-amino-ethyl-urea (CAU) as a volatile corrosion inhibitor (VCI). The gas volatility of CAU was investigated by volatility reduction ex-periment in confined space and the corrosion inhibition for mild steel was evaluated by volatile inhibiting ability (VIA) test and volatile inhibiting sieve (VIS) test. ACM scanning vibrating electrode technique was applied to study the effect of CAU on the corrosion inhibition of mild steel under a thin electrolyte layer. In addition, X-ray photoelectron spectrometry (XPS) was used to illuminate the mechanism of the film formation for CAU on the steel surface. The volatility of CAU was less and the volatile quantity was about 1.0% after 72 h in a closed space at 50 ℃. The steel specimens had no rust after 20 h volatilization period in the VIA test. CAU promoted the corrosion rate of mild steel to decrease from 311.9 mg/(m2?h) to 64.76 mg/(m2?h) in the VIS test and the corrosion inhibition rate of CAU on mild steel was 79.24%. Nyquist plots of EIS rendered a dispersion effect and the charge transfer resistance of mild steel increased from 1.32 kΩ?cm2 to 3.81 kΩ?cm2 after 30 min CAU pre-film process. CAU could volatilize to the surface of mild steel and formed chemical coordination on the surface through atoms N, O and Fe to form a protective film. CAU has good inhibition effect against the atmospheric corrosion of mild steel.