Polyoxymethylene dimethyl ethers (PODE_n) have aroused widespread industry interests due to the prospects for clean fuel additives or substitutes. The densities of liquid PODE_n, were measured with an oscillation tube densimeter and fitted with the Racket equation. The self-expanding empirical density model has been developed to predict the densities of PODE_n, whose pure and reliable monomer could not be readily available. The density behavior of PODE-PODE mixtures, PODE₃-n-hexadecane and PODE₃-tetralin blends was studied. Results showed the excess volumes of PODE-PODE are negative and approximately equal to zero, indicating PODE-PODE mixtures could be regarded as regular solution at temperatures from 273.15 to 363.15 K. While the excess molar volumes of PODE₃-hexadecane and PODE₃-tetralin blends are positive over the complete mole fraction range. The breaking of self-association of the PODE₃ molecules by dilution effect might make a positive contribution to excess volume besides physical interactions. The densities of practical PODE_n-diesel blends were estimated and results agreed well with experimental data.