This experimental research aims at finding the significant difference in achievement between the students who are taught through bottom up strategy in reading comprehension and those who are not taught using bottom up strategy. The bottom up strategy is the paragraphs decoding process that started on words to words as technical terms in one paragraph, then construction meaning from sentences, into comprehension for the whole paragraph. This research focused on student’s achievement in reading comprehension. The student’s achievement in reading comprehension is built from three points, comprehension, meaning construction, and technical terms. The study relied on the decoding process of outlining the paragraph into a line of idea organization. The decoding process is easily applicable in teaching process. This feature made the computer applications that applied in teaching process is settled as friendly as possible in order to simplify the students. Teknik Informatika Department of Politeknik Aceh, Banda Aceh, the vocational diploma institution, majoring computer informatics systems was selected to the research location of study. Moreover, after 10 meetings of treatments within this study, it was found that the t test form independent t test by quantifying the completion of the value of Mean, Standard Deviation, and Variance from both classes to find sgab. Then, the t test was 1, 92. With the level of significant α = 0, 05 and df = (n1 + n2 – 2) = (30 + 30 – 2) = 58, the t table is 1, 68 (t 0, 95 (40) =1, 68). Thus, the result of t test and t table, it found that t test > t table, by 1, 92 > 1, 68. It is indicated that there is significant difference in achievement between the students who are taught through bottom up strategy in reading comprehension and those who are taught through without using bottom up strategy. On the other hand, Ha is proved to be accepted within this study. Key Words: Bottom up Strategy and Decoding