This short note presents a discussion on the characteristic length that appears in dualporosity models for fractured geological media, via which the empirical characteristic diffusion time is defined. The physical meaning of it is further interpreted here from a more rigorous mathematical point of view, relating the so-called characteristic length or, equivalently, the characteristic time, to a statistically averaged quantity over a local representative volume element that contains numerous matrix blocks. Each of these matrix blocks will be of distinct characteristic lengths or times unless the geometrical shapes and sizes (in an effectively volume-equivalent way) of them are identical. Theoretically, those characteristic lengths could be statistically determined through measurement of their typical distributions. Thus, the discussion presented in this article may permit one to have greater insight into the nature of these two parameters, and may also allow a laboratory approach to measure them to be developed.