引力常数G是一个与理论物理、天体物理和地球物理等密切相关的物理学基本常数。目前国际上测量引力常数G的现状是各个实验小组给出的结果在误差范围内不吻合。因此，采用新的方法或新的途径测量引力常数G具有重要的科学意义。在国际上普遍使用的扭秤周期法测G实验中，扭秤振幅通常为数毫弧度，往往需要积累数天的数据来给出高精度的扭秤周期，这对环境的稳定性提出了相当高的要求。因此，增大扭秤运动的振幅是提高测G精度的一个潜在方向。本项目拟开展室温下大振幅扭秤测G的实验方案和前期研究，旨在通过理论建模分析给出大振幅扭秤测G实验的优化设计和可行性报告。同时，通过初步的大振幅扭秤实验实现振幅和周期的高精度测量，解决大振幅下环境振动干扰、温度梯度、电场和磁场影响、非线性效应等关键问题，为后续开展高精度的大振幅扭秤测G实验提供理论指导和技术支撑。

As a fundamental physical constant, the gravitational constant G plays an important role in fields of gravitation, cosmology, geophysics, and astrophysics. The current state of G measurement is that the values determined by different groups are in poor agreement with each other, which may be caused by the unrecognized systematic errors existed in different methods. Therefore, it is of great scientific significance to measure the gravitational constant G using new methods or new ways. In G measurements with the time-of-swing method, the amplitude of the torsion pendulum is usually several mill radians, and it is often needed to spend several days to accumulate data for determining the period of pendulum with high precision. Therefore, increasing the amplitude of the torsion pendulum to improve the measurement precision of the period is a potential direction in further G measurement with higher precision. This project intends to carry out the experimental scheme and preliminary research of G measurement with larger amplitude at room temperature, and give the optimal design and feasibility report through theoretical modeling analysis. At the same time, we want to do some previous experiments for measuring the amplitude and period with large amplitude torsion pendulum, and solving the key problems, such as the nonlinear effect under large amplitude, influence of background electromagnetic field, influence of ground vibration, temperature stability control, etc. This research is a groundwork for us for aiming to measure G with large amplitude with uncertainty of less than 15 ppm in next step.