The microfluidic technology can produce temporal and spatial stable concentration gradient, which benefits quantitative investigation of living cell chemotaxis. To date, the study of chemotactic effect normally neglected the cell volume and the impact of cell motion. In this paper, the impact of a moving sphere cell on the concentration field was investigated by changing the Peclet number, the velocity of cell and the direction of movements. Results show that the deviation of the maximum concentration difference around a moving cell and a stationary cell at the same spot is close to a constant after a certain time. The maximum concentration difference around a moving cell can be replaced by that of a stationary cell with corrections. This conclusion is valuable to further quantitative chemotactic research.