Small-diameter array laterolog technology is studied for through bit logging. The size structure of the electrode sonde is determined, and the borehole, surrounding rock and invasion response characteristics of the small diameter electrode sonde are studied by the numerical simulation method, compared with the response of the conventional large-diameter electrode sonde. The response characteristics of small-diameter electrode sonde in inclined and horizontal well are studied, and the influence of deviated angle and formation resistivity anisotropy is analyzed. The results show that for the small-diameter electrode sonde, the borehole influence chart needs to be remade, and the response characteristics of surrounding rock and invasion are basically the same as those of the conventional large-diameter electrode sonde. With the increase of deviated angle and anisotropy coefficient, the apparent resistivity increases, and the curve separation is bounded by 60° angle, showing the characteristics of high and low invasion respectively. The cross chart of horizontal resistivity and anisotropy coefficient can be made by using the ratio and mean value of apparent resistivity. It provides a foundation for the development of small-diameter array laterolog technology and the interpretation and evaluation of deviated and horizontal wells.