Line commutated converter-based high voltage direct current (LCC-HVDC) can be widely used in long-distance large-capacity power transmission, but its AC side requires the installation of a large amount of filtering equipment and reactive power compensation devices. This equipment occupies a large area and is not flexible, restricting the development of this scheme. To address this, self-adaption statcom and line commutation converter (SLCC) technology with a static synchronous compensator (STATCOM) in parallel on the valve side can achieve continuous regulation of reactive power by virtue of its continuous adjustment characteristics. This paper analyses the working principle and commutation process of SLCC, and proposes a coordinated control strategy that combines reactive power compensation and harmonic filtering, introducing reactive power, harmonic, and firing angle compensation and other links to dynamically track and process reactive power and harmonic current. Finally, simulation verification is carried out on the PSCAD/EMTDC platform. The results show that the proposed control strategy can achieve dynamic reactive power compensation and harmonic accurate filtering of the system, accelerate the commutation process, and effectively reduce reactive power consumption and investment cost.