By means of PeggBarnett phase formalism, the phase properties of the field interacting with more Λtype threelevel atoms via Raman coupling in a phase damped cavity are investigated. The influences of decay coefficient of the cavity, the intensity of the field and the number of atoms on the phase distribution as well as its fluctuation are discussed. The results show that if there is absence of the phase damping, the phase distribution oscillates with the period π/λ. It presents a structure of single leaf at t=nπ/λ, but it splits into multileaf structure during the evolution period due to the interaction between the field and the atoms. If there is presence of the phase damping, the obvious leaf structure of the phase distribution becomes obscure and contracts into a circle, which indicates the random distribution of the phase. The larger the decay coefficient is, the more rapidly the phase becomes random distribution. Otherwise，the change of the number of atoms does not affect the leaf structure of the phase distribution, but intensifies the oscillation of the phase fluctuation.