Apropos of English learning, vocabulary learning is one of the most essential parts. Thanks to modern technology, recent years has witnessed scads of vocabulary learning apps springing in the app market which include greatly comprehensive functions. However, among those popular apps, some universal handicaps still exist in the design of the review section, for example, the absence of the freedom for the users to classify the cognitive or priority grade of vocabulary and the low effect of some reviewing methods that could not satisfy the need of the language learners to fully master the orthography of words. This paper aims at contriving an app serving as a supplementary part of English vocabulary learning in order to remedy those inadequacies of mainstream applications or other self-learning methods. In this paper, literature study, graphology, and mathematical modelling are involved. Based on Matlab GUI/App Designer, this paper presents a new method to review English words in which users could customize their lexicon, as well as define the priority of each word and practice spelling of vocabulary on an hourly-based system instead of a daily-based one that most of the existing online platforms adopted. Through creating a discrete probability density function for each word, this app could forward a random word in the glossary for users to practice orthography, obeying the probability density distribution that has a mathematical relationship with familiarity and priority of the words as well as the time factor (Ebbinghaus forgetting curve). Thus, users could thoroughly grasp the orthography of target words.