Complex sentence: On March 8th, the CCP called up Chengdu Conference, which changed the production target of Nanning Conference to the first production plan, and set up a higher target as the second production plan.
Split into simpler sentences: On March 8th, the CCP called up Chengdu Conference. This conference changed the production target of Nanning Conference to the first production plan, and set up a higher target as the second production plan.