The rotation equation for angle θ between molecular axis and laser polarization direction that described spatial alignment and orientation of molecules in intense femtosecond laser fields has been deduced. A Gaussian laser pulse and the increasing of internuclear distance during the process of molecular muti-electron dissociative ionization and Coulomb explosion are considered. The orientating process of molecules N2, H2, CO, Br2, I2, CO2, and CS2 is investigated by solving numerically the deduced rotation equation for angle. Calculating results show that the linear polarizability and the damping force play an important role in the angular rotation of molecules in conditions of 800nm laser wavelength and 1015W/cm2 laser intensity. Calculating results also indicate that the majority of dynamic alignment for the light molecule N2, H2, CO and CO2 takes place before the molecule ionizes and begins to dissociate. However for the heavy molecule Br2, I2 and CS2, most dynamic alignment occurs during the process of molecular dissociation. The extent of molecular alignment are extensively calculated and discussed.