With the continuous advancement of drilling technology, more and more gas fields both domestically and internationally are adopting special types of wells such as multi-well pads, directional wells, and horizontal wells during their development processes. Correspondingly, the frequency of well testing operations in highly deviated wells has also increased. However, in such operations, the frictional resistance between the conventional instrument string and the wellbore is relatively high, and the instrument string is prone to sticking during its upward or downward movement in the well, which brings many difficulties to the construction process.To address this challenge, we have carefully designed a set of specialized tools specifically for well testing operations in highly deviated wells. The design of these tools is innovative, and we have successfully developed key components such as the eight-wheel roller joint and the articulated roller joint. The entire set of tools not only significantly reduces the frictional force between the instrument string and the wellbore but also effectively shortens the rigid length of the instrument string, thereby greatly enhancing its passage performance. After field trials in multiple wells, the results show that incorporating the specialized well testing tools for highly deviated wells into the instrument string can effectively improve the quality and safety of the construction, providing strong support for the smooth conduct of well testing operations in highly deviated wells.