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To explore wireless underground sensor network (WUSN) node deployment, signal transmission and the channel characteristics in the soil, the relationship among radio frequency signal propagation characteristics of AG—UG, UG—AG and UG—UG communication mode under wireless channel and node burial depth, horizontal inter-nodes distance and soil water content were studied with 240, 433 and 868MHz carrier frequency for configuring wireless underground sensor networks in the soil. The experiment demonstrated that the maximum and minimum determination coefficient R2 of 24 models for goodness of fit were 0.997 and 0.910, respectively, which was the effect of node burial depth and soil water content on RSSI and BER in AG—UG and UG—AG communication. And that maximum and minimum R2 of 12 models for goodness of fit were 0.971 and 0.866, respectively, which was the effect of horizontal inter-nodes distance and soil water content on RSSI and BER in UG—UG communication. Besides, three-dimensional surface of RSSI was built with frequency of 433MHz, which could reflect the exact wireless signal propagation characteristics in the soil environment, and the model verification experiment was conducted through SPSS software. In the AG—UG and UG—AG communication, the minimum R2 of goodness of fit was 0.954, the maximum was 0998, and root mean square error was in the range of 0.729～3.198dBm. In the UG—UG communication, the minimum R2 of goodness of fit was 0.854, the maximum was 0960, and root mean square error was in the range of 3.238～6.553dBm. Validation results showed that the model could better predict the received signal strength in different communications. The results can provide technical support for building of wireless underground sensor network system in the soil.