When some test results was dealt with,an odd problem was found that the rotation-symmetrical stress calculated from Rami's formula couldn't according with the test phenomena if the ratio between outer radius and the inner radius was more large for the cement cylinder with thick wall.In this paper,the theory results deduced from Rami's formula was compared to the test data,and it was found that only when the ratio between outer radius and the inner radius was less than 2.0,the stress calculated from Rami's formula agreed with results.