The invention provides a system for conversion between analog domain and digital domain with mismatch error shaping, including a DAC, a first injection circuit coupled to the DAC, and a second injection circuit coupled to the DAC. The DAC generates a first analog value in response to a first digital value, and generates a second analog value in response to a second digital value. The first injection circuit enables an analog injection value to be injected to the second analog value when the DAC generates the second analog value, wherein the analog injection value is converted from a digital injection value formed by a subset of bits of the first digital value. The second injection circuit injects the digital injection value to the second digital value, or combines the digital injection value and a related value obtained according to the second analog value.