In this paper, the concept of the self-absorption coefficient is discussed using the concept of escape factor. The calculation methods of the escape factor for any profile and any atom cavity are discussed. For the spherical geometry, the escape factors ï(r) at any position r in a spherical geometry plasma (with the radius R) for Lorentzian and Holtsmarkian profiles are calculated for the first time, and a general expression is obtained. As an example, for the sodium330.3nmresonance line, the total radiance and the real radiance are calculated, and the self-absorption coefficient for the resonance line is discussed. This discussion will be useful for the study of escape factor and the self-absorption of spectral lines.