The value of exports amounted to $15.4 billion, also up 5% year on year, the GPCA said.
While 65% of the export volume to China consisted of basic, intermediate and chemicals exports, polymers made up 33% and fertilizers 1%.
Saudi Arabia accounted for 64% of the export volume to China, valued at almost $10 billion, the GPCA said in a statement.
It was followed by the UAE, (11% at almost $2 billion) and Kuwait (10% at about $1.6 billion).
The statement said it was "inevitable" that GCC producers will be feeling the pinch from slowing Chinese demand for petrochemical products.
"China's self-sufficiency in some petrochemicals and polymers is also increasing," Abdulwahab Al-Sadoun, GPCA secretary-general, said in the statement. "But despite these challenges, GCC exports have continued to perform well and in the long run, there will still be substantial room for petchem imports to China."