In order to improve the solution processability of traditional thermoplastic polyimide (TPI) and enhance its adhesion and heat resistance, several soluble thermoplastic polyimide (TPI) resins were prepared from different commercial dianhydride monomers and self-made diamine monomers with pyridine and diphenyl ether structures and active phenol side groups or benzene side group in the main chain through the two-step method. And then the corresponding TPI films and flexible copper clad laminates (FCCLs) were prepared. The properties of TPI resins were analyzed by solubility test and gel permeation chromatography (GPC). The structure, water absorption, mechanical properties, and dielectric properties of TPI films were tested, and the related properties of the FCCLs were also tested. The results show that all the TPI resins can dissolve in strong polar organic solvents such as NMP, and the glass transition temperature (T_g) and 5% thermal weight loss temperature (T_5%) of the corresponding films are in the range of 236.8-325.6℃ and 508.7-553.7℃, respectively, and the residue rate at 800℃ (R₈₀₀) is higher than 64%. The coefficient of thermal expansion (CTE), tensile strength, elongation at break, and water absorption is in the range of 56.36×10^-6-78.30×10^-6℃^-1, 64.93-109.18 MPa, 9.09%-24.60%, and 0.74%-3.75%, respectively. The dielectric constant and dielectric loss of TPI-4 with better comprehensive properties are also lower than that of other samples, and the peeling strength of the corresponding FCCL reaches 0.95 N/mm, but it can only pass the floating welding test at 288℃ for 10 seconds. In addition, the polar phenol side group in TPI-4 not only ensures its organic solubility, but also significantly enhances its heat resistance and mechanical strength, and also reduce its CTE. The existence of reactive phenol side groups provides great convenience for the subsequent chemical modification of TPI. By adding a small amount of cyanate ester resin (CE01) to modify the TPI, the peel strength and the floating welding resistance of the responding FCCLs can be obviously improved.