I have continuity between the two pole of the power cord of my fridge when I unplug it.Is this normal situation or I have a short cut
Presumably the inside of the refrigerator has warmed enough that the thermostat is calling for cooling. Therefore, the motor is trying to start. That means it is attempting to pull "Locked Rotor Amperage" from the power supply, which is considerable. So Barry's answer applies; just change "transformer" to "motor" (since they are quite similar anyway).
I am assuming that you are not experiencing a problem at this time. Most likely, there is a motor inside the refrigerator with the run winding connected to the power cord. If you measure the resistance between the prongs of the cord with a ohmmeter, then you are measuring the DC resistance of the motor run winding. This will be low (maybe 10's of ohms) although not a direct short (say less than 1 ohm). As pointed out, if there were a real short circuit, then the circuit breaker would blow.