Effect of shifts in pH of the medium and temperature on cell growth and production of carboxymethylcellulase (CMCase) by a recombinant Escherichia coli JM109/A-53 was investigated. Lower initial pH (pH 7.0) of the medium and higher temperature (40 ℃) stimulated cell growth of E. coli JM109/A-53, whereas higher initial pH (pH 8.0) and lower temperature (35 ℃) enhanced production of CMCase. The maximal production of CMCase was obtained when initial pH of 7.0 and temperature of 40 ℃ were simultaneously changed to 8.0 and 35 ℃ after 36 h. The production of CMCase with simple shifts in pH and temperature was 783.1 U/mL, which was 2.13 times higher than that under optimal conditions for cell growth. This indicated that a simple process with shifts in pH and temperature could be economically applied for enhanced production of CMCase by E. coli JM109/A-53 with industrial scales.