The electric field measurement sensitivity based on the Rydberg atomic vapor cell has great theoretical advantages over traditional dipole antennas. We combine the Rydberg atomic heterodyne receiver and the Mach-Zehnder interferometer (MZI) with high phase detection sensitivity to evaluate the system reception sensitivity based on the transmitted laser phase shift. Numerical results show that the probing laser frequency detuning can improve the system detection sensitivity. It also shows that the phase-based readout approach of heterodyne Rydberg atomic receiver based on MZI can achieve better sensitivity than the intensity-based readout approach of heterodyne Rydberg atomic receiver.