In this work, the performance analysis of Bit Error rate (BER) Vs Ratio of Bit Energy to Noise Power Spectral Density (Eb/No) of simulink based DS-SS system is presented using the BERTool module. We have simulated the DS-SS system simulink model with 16-QAM, 32-QAM 64-QAM modulation techniques and from the simulation results it is found that bit error rate is increasing as the value of M increases i.e bit rerror rate of 64-QAM is higher than the bit error rate of 32-QAM. Similarly bit error rate of 32-QAM is higher than the bit error rate of 16-QAM. Also DS-SS system with M-QAM modulation using different spreading sequences (PN, Gold, Kasami) is simulated for BER analysis and found that DS-SS system showed better BER performance with 32-QAM and 64-QAM modulation technique using Gold sequence and Kasami sequence respectively. From the simulation results, it is concluded that by choosing the type of modulation technique and spreading sequence can enhance the performance of DS-SS system.