US Sub fleet:
Ohio class (18 in commission) — ballistic missile submarines, 4 converted into guided missile submarines (SSGN's).
Virginia class (5 in commission, 1 under construction, 6 on order) — attack submarines
Seawolf class (3 in commission) — attack submarines
Los Angeles class (49 in commission) — attack submarines
Chinese Sub fleet:
SSN
Type 091 Han class - 5 boats
Type 093 Shang class - at least 2 confirmed, more under construction
SSBN
Type 092 Xia class - 1 boat
Type 094 Jin class - at least 2 confirmed, more under construction
Diesel-Electric
Type 033 Romeo-class - mostly retired, 8 remain in service
Type 035 Ming-class - version of Romeo, 15 boats
Kilo-class - 4 Type 877EKM and 8 upgraded Type 636 in service
Type 039 Song-class - 13 boats [1]
Yuan-class - 1 boat + 2 under construction
SSGN Type 092 Xia class - under construction/conversion
SSG Project 629 submarine - at least 1 in service
Add the combined years of service experience between the two as well (and FWIW, subs are supposed to be able to sneak up on their enemy, it's kind of the whole point), I'd say that in a way situation the USN wouldn't just pwn the Chinese, in active engagement they'd wipe the Chinese sub fleet out.