This research aimed at: (1) describing types of sentences based on their number of clauses; (2) describing the forms of sentence constructions in the essays written by students of Yunnan Minzu University (YMU); (3) describing errors in sentence constructions in the essays written by students of Yunnan Minzu University (YMU). This research is a descriptive qualitative research whose samples were taken from the essays of Yunnan Minzu University students who were taking credit transfer program at the State University of Yogyakarta. The data collection techniques used were reading techniques and recording techniques which were in the form of written documents. The data analysis was done using distributable methods with techniques for the direct elements. The data validation was done by observing and reading it over repeatedly, maintaining the perseverance of researcher in analyzing the data, doing triangulation of data, as well as conducting discussions with lecturers and peers. The results of the research were as follows. First, types of sentences based on their number of clauses in the essays wriiten by YMU students were simple sentence and compound sentence. Second, the sentence constructions of the simple sentences in the essays written by YMU students were: S+P+(K); S+P+O+(K); S+P+O+Pel; S+P+Pel+(K); and P+S+(K). The sentence constructions of the compound sentences in the essays written by YMU students were: S+P+ conj+ (S)+P+(O)+(Pel)+(K); S+P+O+(K) +conj+ (S)+P+(O)+(K); S+P+Pel+(K) +conj+ (S)+P+(Pel)+(K); S+P+K +conj+ P; P+S +conj+ P. The sentence constructions of the compound complex sentences in the essays written by YMU students were: S+(relative pronoun+relative clause)+ P+(O)+(Pel)+(K); S+P+( relative pronoun+relative clause) +P+(O)+(Pel)+(K); S+P+O+Pel+( relative pronoun+relative clause) +K; S+P+O+( relative pronoun+relative clause) +Pel+K; S+P+O+Pel+( relative pronoun+relative clause) +K; conj+ subordinate clause + main clause; dan main clause +conj+ subordinate clause. Third, the types of errors found in the essays were: (a) the absence of a subject in a sentence; (b) the absence of a verb in a sentence; (c) the absence of both subject and verb in a sentence; (d) the absence of a conjunction between sentences.
