The the simplest version of the Bak-Sneppen model of self-organized biological evolution with random interaction structure is considered. It's dynamics is described in the framework of master equation. The master equations can be solved exactly both for infinite system and for finite one. The equation for pair correlation function are solved exactly for infinite system. The dynamical regime of self-organized criticality in this model appears to be similar to one of completely integrable systems. Analysis of main characteristics of dynamics take it possible to revive the most essential feature of dynamics.