Abstract: The current research work lacks systematic considerations of stiffness changes in loading process for inner concave cable-arch structure． An intensive study was performed based on the experimental exploration and finite element analysis． Firstly，a principle for calculations of global stiffness was proposed for inner concave cable-arch structure． Then， the testing data obtained from the experimental model were analyzed with that principle． Considering both geometrical and material nonlinear effects，multiple finite element analysis models were built by varying the rise-to-span ratio and cross section of both arch and cable and initial imperfections of a typical inner concave cable arch structure． The corresponding analysis was also completed，which verified that the initial stiffness was mainly dependent on rise-to-span ratio and cross section of arch rather than those of cable． Moreover，the results obtained by both experiment tests and finite element analyses indicated that the load-displacement curve corresponding to elastic stage was obviously nonlinear when the difference between arch rise-to-span ratio and cable rise-to-span ratio was less than 0. 055．