本文包含兩個研究，旨在探討學齡前幼兒口語語法理解能力的發展情形，並檢視其相關因素的影響。研究一係應用「學前幼兒與國小低年級兒童口語語法能力診斷測驗」，分析臺東地區67位幼兒在口語語法理解的情形，結果顯示，幼兒在整體詞彙語法概念的理解通過率為85%∼100%，除了「左、右」。在語法結構能力部分，僅因果關係複雜句的理解通過率達84%，其餘皆未達80%。研究二依據研究一的結果進行幼兒口語語法理解測驗的編修，以臺北市、新北市、苗栗縣、高雄市及臺東縣共11所公、私立幼兒園，月齡51∼77個月的167位幼兒為參與對象。結果該測驗在鑑別度與難易度均屬中等，亦具有良好的可信度與穩定度。根據結果顯示，4歲半幼兒在空間、大小、數量、包含與差異等項目通過率為86%∼99%。在語法結構知識部分，4歲與6歲幼兒在並列、轉折與假設的複句具有差異，4歲幼兒在時間副詞與遞進複句的通過率為30%。在性別變項上發現女生的口語語法理解能力顯著優於男生，在年齡變項上，隨著年齡增長，幼兒在口語語法理解能力的表現愈好。幼兒家庭的社經地位愈高，其口語語法理解表現亦隨著愈高。另以聽覺詞彙與幼兒工作記憶的顯著關係檢驗其關係。本研究依據結果，進行討論並提出建議。

Study 1 analyzed the oral syntax comprehension performance of preschoolers in Taitung, Taiwan, by using oral syntax comprehension tests. The primary findings were as follows: The children easily understood the meaning of lexical categories in Chinese syntax but had trouble understanding the phrase-structure rules and sentence lexical categories in terms of linear word order. The results of Study 1 were used to revise the oral syntax comprehension test items for Study 2. Study 2 investigated the development of syntax comprehension ability in Taiwanese preschoolers by using an oral syntax language test, which contained 45 items. All the items were individually administered to 167 native-Mandarin-speaking children from public preschools in Taipei City, New Taipei City, Miaoli County, Kaohsiung City, and Taitung County. Participants were aged between 51 and 77 months. Item analysis revealed that the difficulty and discrimination of the test was moderate. The tests also had acceptable validity and stable reliability. The results indicated that, concerning word linguistic content, 4-year-old children were able to distinguish between the size of the difference, the number of comparisons, all elements and their parts, and classifier constructions. Regarding syntactic structure knowledge, significant differences were observed between the 4-year-old group and the 6-year-old group for juxtaposition, transition, and hypothetical complex sentences. Knowledge of time adverbs and the ability to form progressive complex sentences were insufficiently developed in 30% of the 4-year-old children. Several significant differences were observed in oral language ability in terms of age, sex, and socioeconomic status. Regression analysis results supported the discourse of accepted vocabulary, Chinese verbal working memory ability, and semantic grammar. This paper discusses the current findings and provides relevant recommendations.