Traditional compression algorithms of OFDM signals with low compression ratio and signal to quantization-error ratio(SQR) come along with a high error rate, which fail to meet the requirements of OFDM systems. To achieve the high compression ratio and the low e rror rate, a new algorithm is proposed based on a combination of clipping with tail plug (CTP), geometric series companding (GSC) and partial sample calibration (PSC). The new algorithm can achieve the nearly loss-less compression and the compression ratio can be as high as 1.86∶1 with a error rate less than 10-7, while SQR corresponding to the quantization error is 70 dB in 4096-QAM OFDM signal modulation schemes meeting the requirements of the FTTdp+GDSL systems well.