The negative effect of spacecraft inside isolated conductor surface charging is more unobvious, causing more serious direct and potential harm. Considering the electrons and ions, the secondary electron emission, according to the kinetic theory of gases and combing the theory of particle in Maxwell velocity distribution function, calculate general expression in a plasma environment unbiased solid surface charging. Using the voltage general expression, we deduce the expression of energy and electric quantity, discuss the relationship between energy of isolated conductor's electrostatic field and surface as well as space environment in special environment, compare the energies of electrostatic field in different environments and different surfaces with electromagnetic pulse discharge damage of ground electronic components, and finally summarize the rules of area effect of isolated conductor's surface charging.