The invention proposes a 
linear quadratic fault-tolerant control method for infinite 
time domain optimization of a batch process. The method firstly establishes a multi-stage 
state space model by collecting input and output data, further converts the 
state space model into an extended 
state space model including state variables and output tracking errors, uses a switching 
system model for representation, then designs a controller which can be flexibly adjusted in real time in an infinite 
time domain, and finally aims at different phases to design dwell time which relies on the 
Lyapunov function. The method has the advantages that firstly, an 
optimal control law which can be flexibly adjusted in real time is designed in the infinite 
time domain to 
resist the influence caused by 
actuator failure and external interference on a 
system, so that the stable running of the 
system under the influence is ensured, and the system has 
optimal control performance; secondly, a switching law is designed without the need for setting of other parameters, and a value is obtained directly; the method accurately determines the 
running time of each stage, so that the 
running time of the system is shortened, product quality is ensured, and production efficiency is improved while the stable running of the system is ensured.