Hello Khalid mostafa,
You are right, the voltage must be "0 V" in real circuit.
But I think, you use only a simulation to control it. In simulation you have not real componets and measure instruments, but ideal components. So your voltage meter has an unlimited input resistance and the capacitor will not discharge by the instrument.
For real test, put a resistance of 10MΩ parallel to the instrument as simulation of the inner resistance. S o the voltage will drop to zero.