The paper presents a novel series solar thermal liquid desiccant air conditioner (STLDAC). The system has unique features including “zero carry over”, “no corrosion” and high performance. The STLDAC is based on the combination of an air conditioner and a regenerator unit. The key components of air conditioner is an inner cooling dehumidification core (ICDC), the integration of ICDC with Psychometric Energy Core (PEC) to provide further cooling and integration of I ＣDC with Micro Heat/Mass Cell Cycle Core (MHM3C) to achieve a high enthalpy recovery. The regenerator uses a low grade thermal energy and a two-stage-regenerator to achieve a COP above 1 at a thermal temperature of less 95℃. The paper describes the design, Cycle and application of the solar thermal desiccant air conditioner.