Error-related　potentials　(ErrP)　are　changes　in　EEG　signals　that　can　be　elicited　when　users　perceive　errors.　Recognising　ErrP　can　help　improve　the　performance　of　P300　Speller.　However,　it　is　a　hard　task　due　to　the　low　signal-to-nosie　ratio　and　high　variability　from　trial　to　trial.　In　this　study,　a　novel　method　is　proposed　to　reveal　the　difference　in　time　series　pattern　between　single　trial　EEG　epochs　that　contain　ErrP　and　ones　that　do　not　contain　ErrP.　For　testing　our　approach,　four　healthy　subjects　were　recruited　to　take　part　in　P300　Speller　experiments　with　feedback.　The　performance　was　evaluated　with　sensitivity　and　specificity　metric.　The　attained　results　were　54.7%,　89.6%　respectively.