二十一世纪以来，B工厂和北京谱仪III实验发现了大量新的类粲偶素（也称XYZ）粒子，它们中很可能存在分子态、多夸克态、混杂态等非常规介子或奇特态强子。BESIII实验是目前在类粲偶素能区运行的亮度最高、最稳定的正负电子对撞实验，作出了包括发现Zc(3900)在内的多项重要成果。本项目计划在4至4.9GeV之间继续采集数据，深入研究Zc(3900)、Zc(4020)等粒子的性质，寻找含奇异夸克的带电类粲偶素Zcs；精确测量正负电子对撞产生的含粲介子末态和含粲偶素末态的截面，确定矢量粲偶素（psi）和类粲偶素态（Y）的共振参数及产生与衰变性质；利用矢量粒子辐射跃迁寻找X(3872)、X(3930)、Y(4140)等类粲偶素粒子和S波及P波粲偶素。这些结果将加强对强子结构的深入认识，促进量子色动力学理论的完善和发展；同时我们将着眼于可能出现的新物理现象，发现新的物理规律。

Many charmoniumlike states were discovered at the B-factories and the BESIII experiment in the last two decades, while some of them are good charmonium candidates as predicted in different models, most of these states have exotic properties and they are possible tetraquark states, molecules, or charmonium hybrids. BESIII is now play leading role in the study of these states. We plan to take more data at center of mass energy from 4.0 to 4.9 GeV to search for new charmonium and charmoniumlike states and to understand the nature of these states. We will measure more modes related to the Zc(3900) and Zc(4020), try to understand the nature of them, try to search for Zcs, the charged charmoniumlike state with a strange quark; measure in high precision the e+e- annihilation cross sections of final states with charmed mesons or charmonium states, to understand the excited vector charmonium states and the vector Y states; search for the C-even S- and P-wave charmonium and charmoniumlike states such as the X(3872), X(3930), and Y(4140). These studies will deepen our understanding of the hadron structure and the theoretical description of the strong interaction in the regime of quark confinement. In the mean while, we will keep an eye on possible new phenomenon in the data and try to find new experimental rules from the data.