A compensated compact microstrip resonant cell (C-CMRC) with photonic band-gap (PBG) performance is presented in this paper. Two open microstrip stub-lines are added at the center of the compact microstrip resonant cell (CMRC) to compensate for the unbalanced change of inductance and capacitance in low pass band. It can significantly improve the return loss and insertion loss. Furthermore, the C-CMRC with capacitive loading leads to a stronger slow-wave and enlarged stop-band bandwidth. A low pass filter with 3 C-CMRC resonators in series has been designed according to the PBG performance. The period is only 0.15λg due to the slow-wave effect. Comparison with the general PBG period of 0.5λg, the circuit size is reduced effectively. The original CMRC and the C-CMRC with open stub lines are designed, fabricated and measured to validate the improved performance. A low pass filter with 3 C-CMRC resonators is also designed with 1.26dB insertion loss below 1.8GHz and more than 25dB stop-band from 2.6 to 9GHz.