Optimization of phenolic extraction from Orthosiphon stamineus was carried out in present study by investigating the effects of ethanol concentration (0-100%, v/v), extraction time (60-300 min) and extraction temperature (25-65oC) on the phenolic recovery using single factor experiment. Total phenolic content (TPC), total flavonoid content (TFC) and condensed tannins content (CTC) were used for determination of phenolic compounds while 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radical-scavenging capacity and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging capacity were used for evaluating the antioxidant capacities of crude extract. Experimental results showed that all extraction parameters had significant (p<0.05) effect on phenolic contents (TPC, TFC and ABTS) and antioxidant capacities (ABTS and DPPH) of crude extract. The optimized conditions for phenolic extraction were 40% ethanol for 120 min at 65oC with values of 2003.4 mg GAE/100 g DW for TPC, 1611.9 mg CE/100 g DW for TFC, 202.4 mg CE/100 g DW for CTC, 765.4 µmol TEAC/100 g DW for ABTS and 2180.9 µmol TEAC/100 g DW for DPPH. DPPH was found to be positively significantly correlated with TPC but negatively significantly correlated with CTC under the influence of ethanol concentration. As a function of extraction temperature, all antioxidant compounds assays (TPC, TFC and CTC) were negatively correlated with antioxidant capacities (ABTS and DPPH).