The present invention provides an existing building reconstruction balance weight self-adaptive control device. A background server is configured to perform analysis of structure state data collectedby a structure state real-time monitoring device, an analysis result is employed to calculate an existing building balance weight increment or decrement by taking an adaptive control method as a basis, control information is sent to a balance weight regulation device, a balance weight object is injected into a rigid cavity through the balance weight regulation device to achieve increasing of the balance weight, and the balance weight object is sent out through an outflow to achieve decreasing of the balance weight so as to achieve real-time balance maintenance of the existing building structure. The existing building reconstruction balance weight self-adaptive control device is convenient and rapid in increasing and decreasing of the balance weight, employs a linear mode to increase the balance weight object and is safer to increase and decrease the balance weight load; the structure state real-time monitoring device can timely understand the structure state change; and the structure state is employed to reflect and regulate the weight of the balance weight, the structure balance control is more accurate, and the structure quality safety is better guaranteed.