The invention relates to a method for identifying a capital English letter automatically based on fixed strokes of a mobile phone, which comprises an estimation method of a mobile phone movement track and a matching identification method of the fixed strokes. The method is used for inputting capital English letters and a space key; a user can input the capital English letters in the space through the estimation method of the mobile phone movement track and the matching identification method of the fixed strokes and by using a three-axis acceleration sensor mounted in the mobile phone. The method is applicable for a user with a relatively low visual ability or a circumstance in which a mobile phone keyboard or a touch screen is inconvenient to use; meanwhile, according to the method, a three-axis sensor is corrected, and null shift and gravity are removed, so that the calculation of the mobile phone movement track is more accurate, correct input is accordingly obtained, and the user can write in the space for inputting as using a pen.