A new configuration with only one cylindrical attracting mass for the deter
mination of Newtonian gravitational constant G is proposed. The uncertainty
in G introduced by determining the separation between the attracting masse
s in usual configurations can be avoided naturally, due to only one cylinde
r being used. Furthermore, an optimum ratio of the separation between the t
est masses to the length of the attracting mass can greatly reduce the unce
rtainty in determining G due to the uncertainty of measuring the separation
between the test masses.