i want a calculation which get power and turque and speed of a hydroalic pump , then give the displacment or flow rate of it .

I think you need to provide more information. Usually you have a required amount of work, then you size a pump accordingly.

All hydraulic work is based on a simple equation Work or Energy = Pressure x Volume Since hydraulic pumps work with incompressible fluids Power which is the rate of work can be expressed by the equation Power = Pressure x flow rate If you know the displacement of the cylinder or working chamber you can calculate amount of power per cycle and from that you can calculate the torque. I realize that this is a little sketchy, but before you can go much farther you need to determine what type of hydraulic pump you have. Is it a gear pump, a piston pump, or other type of pump.

power=(d*g*Q*H)/1000 pressure=d*g*H power=(2*pie*N*T)/60 where d=density of the pumping fluid in kg/m^3,(for water 1000kg/m^3) g=acceleration due to gravity (9.81m^2/s) Q=fluid flow rate in m^3/s H=head of the fluid in metrs pie=22/7 N=speed of the impeller in rpm T=torque in N-m. i think by using these derivations u can find out the value of power.