  The sets of the synchronous equations are derived from the sets of
non-synchronous equations The analytical solutions are given by solving the set
of differential equations. The results of the evolutionary tendency of the
orbit-spin are that the semi-major axis shrinks gradually with time: the
orbital eccentricity dereacses gradually with time until the orbital
circularization; the orbital period shortens gradually with time and the
rotational angular velocity of primary component speed up with time gradually
before the orbit-rotation achieved the circularization The theoretical results
are applied to evolution of the orbit and spin of synchronous binary stars
Algol A, B on the main sequence phase The circularization time and life time
(age) and the evolutional numerical solutions of orbit and spin when
circularization time are estimeted for Algol A, B. The results are discussed
and concluded.
