Spontaneous polarization (P-s), tilt angle (theta), helical pitch (p) and densytometric (rho) characteristics versus temperature and concentration of chiral dopant have been measured for FLC mixture. On the base of computer modelling the molecular dipole moment (mu), transverse (alpha(t)) and longitudinal (alpha(1)) molecular polarizabilities as well as angle (gamma and phi(0)) between the vector mu and main long n and short 1 molecular axes of inertia have been calculated. Knowing the molecular parameters mu, alpha(t), alpha(1), gamma and phi(0) and state parameters theta, p, spontaneous polarization P-s has been calculated as the vector sum of the components of molecular dipole moment mu(perpendicular to) perpendicular to the tilt direction. To do it the Zeks(1) rotational potential modified by us(2) has been used. After comparing spontaneous polarization P-s taken from experimental and obtained from theoretical approximation the biased rotation parameter eta has been calculated.