Abstract: To explore the ignition and combustion characteristics of n-pentanol/n-dodecane binary fuel,a natural flame luminosity method, schlieren method, formaldehyde laser-induced fluorescence method, and OH* chemiluminescence method were used in a high temperature high pressure constant volume combustion vessel to study the ignition delay period,flame development,combustion intermediate components and flame lift-off length of the n-pentanol/n-dodecane binary fuel. The results show that the binary fuel of P20D80 has longer ignition delay period and flame lift-off length under the same working conditions compared with n-dodecane（D100） fuel.Besides,the initiation of formaldehyde in P20D80 is about 100 μs later than that in D100,which can reduce the generation of soot. Their formaldehyde signal is consumed step by step at the downstream position of the flame liftoff position. Compared with D100,the chemical ignition delay period of P20D80 is longer under different ambient temperature conditions,but as the injection pressure increases,the chemical ignition delay period of P20D80 first becomes larger and then smaller. In addition,under the same working conditions,the difference of the physical ignition delay period of the binary fuel minus that of n-dodecane increases slightly with the increase of ambient temperature,but decreases with the increase of injection pressure reduce.