With the advancement of electronic device fabrication processes and the reduction of chip operating voltages, the performance requirements for rail to rail operational amplifiers have become increasingly stringent, particularly in critical parameters such as offset voltage and slew rate. This paper presents a low-offset, high slew rate rail to rail op-amp design. By cascading a high-gain low-bandwidth amplifier with a low-gain high-bandwidth architecture, constant transconductance is maintained across the rail to rail common-mode voltage range through current distribution principles. The output stage utilizes a feedforward Class AB push-pull amplifier to achieve rail to rail output with enhanced driving capability. A dedicated slew rate enhancement circuit is implemented to address the insufficient output slew rate under large input signals, thereby improving transient response and extending operational bandwidth. Additionally, to mitigate offset caused by process variations, a digital fuse trimming technique is incorporated at the input stage for load calibration. Operational stability is ensured through nested Miller compensation. Post-layout simulation results demonstrate that under a 2.2~5.5 V supply voltage with 1 kΩ and 100 pF load conditions, the op-amp achieves a gain-bandwidth product of 10 MHz, an open-loop gain of 145 dB, a phase margin of 62°, a slew rate of 11 V/μs, and a maximum offset voltage of 70 μV. Compared to conventional rail-to-rail op-amp designs, this architecture effectively reduces offset voltage through trimming technology and significantly enhances slew rate via dedicated enhancement circuitry, enabling the proposed design to drive heavy loads with high precision under constrained power consumption while maintaining superior performance metrics.