A low-power rail-to-rail operational amplifier with enhanced linearity is designed and implemented to address the signal distortion problem of the Class-AB output stage of operational amplifiers. Based on a mechanism analysis of the non-ideal higher-order effect caused by the short channel, a linearly enhanced floating current source structure is proposed, which effectively reduces the circuit gain nonlinearity and decreases the distortion problem during signal processing while controlling the power consumption through the application of the translinear loop. A circuit prototype is fabricated using a 0.18-μm process, and the test results show that the chip realizes a rail-to-rail input-output range with a gain nonlinearity of 5.5×10⁻⁶, a quiescent current of 39 μA, and an open-loop gain of 119.5 dB.