Aiming at the problems of redundant volume, large link loss, and weak anti-electromagnetic interference of traditional FMCW radar transceiver systems in miniaturized devices, this paper designs and implements a highly integrated FMCW radar transceiver SiP module operating in the 4200-4400MHz frequency band, which is suitable for aircraft altimeters. Based on System-in-Package (SiP) technology, the module adopts a 4-layer BT substrate to realize heterogeneous integration of multiple chips. It internally integrates a transmission link, a reception link, and a clock generator. A DDS is used to generate 500MHz~700MHz signals, which are then upconverted to the target frequency band in one step. The module features transmit power control, receive gain adjustment, and frequency-swept waveform configuration. The system is designed with a transmit output power of 20dBm, a maximum receive link gain of 80.5dB, and a transmit-receive isolation of ≥90dB, with a compact package size of only 14mm×14mm. Test results show that the module has a transmit power flatness of less than 1dB, a noise figure of only 4.08dB at maximum gain, and an FMCW signal linearity of 0.012%. It can achieve kilometer-level altitude detection and fully meets the application requirements of aircraft for miniaturization, low power consumption, and high signal stability.