Ultra-deep wells often develop multiple pressure systems within the same open-hole section, leading to a narrow safe density window or even a negative density window. This readily induces the complex situation where kick from high-pressure formations and lost circulation in low-pressure formations alternate or occur simultaneously. To address this problem, a wellbore multiphase flow test facility for complex well conditions was independently developed, and physical experiments covering three types of coexisting kick and loss conditions, different formation characteristics, and different fluid properties were systematically conducted. The flow evolution laws of the gas-liquid two-phase flow field in the wellbore under different coexisting kick and loss conditions were revealed, along with the nonlinear influence mechanisms of loss pressure differential, kick pressure differential, and fluid viscosity on the formation-wellbore coupling response characteristics. A multi-parameter evolution model applicable to actual field condition analysis was constructed. The research results show that: compared with the condition where kick and loss occur in the same layer, the flow evolution of the gas-liquid two-phase flow field is more violent under the upper-kick and lower-loss condition, whereas it is relatively moderate under the upper-loss and lower-kick condition. Under different types of coexisting kick and loss conditions, the liquid loss volume, gas influx volume, and bottom-hole liquid column pressure all exhibit highly symmetric staged evolution characteristics, and these characteristics do not change with the type of condition or with variations in sensitive parameters. Under various complex conditions, the evolution intensity of the target parameters differs as the loss pressure differential changes. As the influx pressure differential increases, the maximum liquid loss volume remains unchanged for each condition, while the decrease amplitudes of the maximum gas influx volume and the minimum bottom-hole liquid column pressure show significant differences. With an increase in the liquid-phase viscosity, the fluctuation amplitudes of all target parameters during the evolution process exhibit a decreasing trend.