Abstract: Several problems in calculating attitude angles of an aeroplane are discussed and their solutions are provided.（1）In order to determine the single valued angle position of an aeroplane,definition regions for attitude angles are given,so that determining attitude angles is facilitated.（2）When denominator（or numerator）of the independent variable in an arctangent function approaches to zero,there are a lot of troubles such as appearance of large error,overflow,etc..The solution is proposed to determine values of attitude angles directly according to whether values of the numerator（or the denominator）are positive or negative when absolute value of the denominator（or the numerator）is less than a small value e,which depends on the demanded accuracy of the system.（3）As the pitch angle 6 tends to a small conic region of ±90°,three degrees of freedom of attitude angles will reduce to two degrees of freedom.Let roll angle γ=0,and choose the other two elements T21 and T11 of the direction cosine matrix,so that calculation of yaw angle ψcan be accomplished.Programme diagram for attitude angle calculation is given and results of mathematic simulation show correctness of the above theoretic analysis.