Since 2008, the degradation of system performance parameters of analog IF receiver has caused the poor reliability and stability and higher failure rate of the CINRAD/SA radar at Jinan. In order to better ensure the normal operation of the weather radar, the IFD (Digital Intermediate Frequency) upgrade project was completed in July 2009. After transformation, the phase noise of the IFD radar is very stable and the velocity information is more credible and accurate. The working principles of the IFD receiver are introduced, with the emphases on the problems in the software and hardware and their solutions about the installation, debugging and transformation of the IFD devices. In addition, the technical parameter tests after transformation is also summarized, to provide references to radar maintenance staff.