The hexagonal close-packed (hcp) metal Be has many potential applications. Much attention has been attracted on its mechanical properties and deformation mechanism. It has been found that the deformation mechanism involves the dislocation slip, twinning and their interaction, which are controlled by temperature, strain rate and initial texture. Typically, the softening and hardening behaviors in mechanical properties can be respectively induced through the elevated temperature and high strain rate. However, the microstructures engineering for properties tailoring in Be is still an open question. In this work, the effect of different initial microstructures on mechanical properties of polycrystalline beryllium was investigated, and the underlying mechanism was revealed by OM, SEM and in-situ neutron diffraction measurement. Three different kinds of microstructures have been achieved in Be by different pre-deformation strategies: (i) room temperature (RT) and the strain rate of 10^-3 s^-1, (ii) 600 ℃ and 10^-3 s^-1, and (iii) RT and 10³ s^-1, respectively. The mechanical properties of the polycrystalline Be are consequently tailored. The results show that, the compressive mechanical response is the hardest for the sample quasi-statically pre-deformed at RT, while is the softest for the dynamically pre-deformed one. The sample quasi-statically pre-deformed at RT possesses the "weak texture" type of initial microstructure, for which the (00.2) plane preferentially bears the compressive strain during the microscopic mechanical response; due to the combined effects of the initially preferred microstructure and induced dislocation, this sample exhibits the relatively obvious deformation-hardening with respect to the other ones. The sample dynamically pre-deformed at RT has the "strong texture" type of initial microstructure and some micro-voids; the (00.2) plane also mainly bears the compressive strain during the microscopic response; however, the deformation-hardening effect is weakened because the existing micro-voids participate the stress partition. The sample quasi-statically pre-deformed at 600 ℃ possesses the "random orientation" type of initial microstructure; each plane for this sample bears the compressive strain equally at the preliminary stage during the microscopic response and then the lattice strain for (11.0) plan increases with the increase of loading stress; for such case, the deformation accommodation inside the sample becomes relatively easier due to the decreased dislocation density. It suggests that the controllable mechanical properties can be realized through collaborative configurations of microstructures at different scales. The material properties can be customized through the microstructure engineering to meet the particular service requirements.