We have studied the magnetic properties and magnetocaloric effect of ball milled CoMn_0.95V_0.05Ge alloy by means of temperature and field dependence of magnetisation measurements. CoMn_0.95V_0.05Ge nano-powders with different particle size distribution were prepared by varying the milling time for 4, 6 and 8 h. The atomic force microscopy (AFM) images showed that the average size of the particles decreases with increased milling time as expected. The nature of the magnetic phase transition has been determined by using Arrott plots, rescaled magnetic entropy change and power exponents of ΔS_M. We found that the nature of the magnetic transition for nano powders has a second order nature, although their bulk counterpart with same composition exhibits a first order magnetostructural phase transition. The observed maximum magnetic entropy change for nano powders is, therefore, slightly lower than that of their bulk counterparts. However a 50 % increasing of relative cooling power for nano-powders is achieved. These results suggest that CoMn_0.95V_0.05Ge nano-powders could be a suitable candidate as working substance for magnetic cooling technology around room temperature.