They have to accept a more normalized - ie slow - rate of economic growth. They have to switch from the non-stop stimulus & extreme debt based approach, to allowing organic growth to mostly take over.
They've been riding an unsustainable approach since the great recession mess tanked the global consumer. Simply put, they have to switch to a sustainable model for their economy. It's a painful process, made worse by the choices of delay that they've previously made.
It's also not uncommon. The US nearly got thrown into a depression by the stupidity of the Fed trying to avoid a recession after 9/11 and the stock market crash post dotcom bubble. You can try to dodge reality, usually though it'll just compound the painful price you pay later. In China's case, the potential price is best represented by what has happened to Japan through their previous attempts to dodge economic reality (via debt, keeping zombie corporations alive, etc).
China's organic rate of growth would be very low (for them, versus the recent past). Strip out the fake numbers, then reduce the stimulus efforts to mostly emergency circumstances, and you'd see something more typical like 2% to 3% GDP growth. That's obviously unacceptable to the government authorities.
The Chinese Government is trying to both delay and buffer that process, of dropping from the previously fast rates of growth to the rates you see in more developed nations. I think they fully understand it's inevitable. They want to minimize the social disharmony of it, for the purpose of retaining their power. The fear of revolution is always present. They're trading future stagnation for present buffering of the downside to dropping rapidly from high growth to slow growth (they'll worry about the consequences of that trade later). China faces the not enviable situation of ending up with a mature, slow growth economy, while still having hundreds of millions of people in near third world poverty. I think that's impossible for them to avoid given the scale of their population, the present phase that it's in in terms of transition, and typical rates of more normal organic economic expansion (whether domestically or in the global economy).
How do you explain to 500 million extremely poor people that the best days of growth are permanently over and they'll never get to become well-off like the lucky ~10% that were in the right places in eastern China 20-30 years ago and got to ride the easy boom? To maintain that fantasy (that everyone will get to participate, even though the party is already over), you need to project extremely high rates of growth. Traditional service economies with their far slower growth can never deliver on that.