China's SSBNs are only effective through their missiles, SLBMs. The latest developed missile, the JL-2, suffers from inadequate range (perhaps 8,000 km with a light payload - one 500 kg warhead). The main inadequacy is the inability, from "bastion waters" (protected by Chinese defence forces) to hit targets in the continental US.
China also lacks the opportunities to fully test (with sufficient secrecy) the JL-2 over its full, estimated 8,000 km range. China lacks Russia's long national length and the US's California to distant Pacific testing range facilities.
Lack of full range testing also prevents the JL-2 being tested for accuracy, as measured by CEP. Lack of CEP assurance denies China knowledge of whether its missiles can destroy enemy missiles in their silos. Computer modelling provides only partial assurance.
As illustrated below the USN and Pentagon appear to continually over-estimate the operational numbers, maturity and capabilities of Chinese SSBNs and SLBMs. Perhaps justification of a high tempo building program for US SSNs and SSBNs comes into this.
It is relevant that the total number of very likely inferior JL-2s mounted by China's four known Type 094s (Jin class) is 48. In comparison only two of the USN's superior Ohio class SSBNs are needed to mount a total of 48 (superior) Trident II D5s.
See the whole article Hans M. Kristensen and Robert S. Norris Chinese nuclear forces, 2015 (July 2, 2015).