本文根據漢藏語的比較，構擬上古漢語與原始漢藏語帶r與l的複聲母。漢藏語的比較顯示，漢語來母（﹡r-, ﹡rj-）、喻四（﹡1-）與邪母（﹡lj-），不但對應藏緬語的r-與l-，也對應藏緬語的br-, gr-, dr-與bl-, gl- （在r-與l-前面有濁塞音）。而後者也同時對應漢語的濁塞音聲母。根據漢藏同源詞的比較並參考藏語構詞法的模式，本文提出前者在原始漢語不帶詞頭，而後者則帶有詞頭的假設。 本文指出原始漢藏語的詞頭（如﹡N-, ﹡s-, ﹡m-等）在消失前曾對原始漢語中某些聲母發生了影響，而在同一個時期原始漢語r-與l-前面不帶詞頭的濁塞音也消失，但帶詞頭的則受到詞頭的保護而保存下來。 本文所提出的構擬，旨在說明詞頭對聲母的影響以及隨後詞頭消失的過程。在結論中並對原始漢藏語帶r與l的複聲母從原始漢藏語到中古漢語之間所發生的變化提出綜合性的說明。

This paper reconstructs consonant clusters with -r- and -l- as the second elements in Old Chinese and Proto-Sino-Tibetan, basing on the comparative study of Sino-Tibetan languages. The comparative study shows that Old Chinese ﹡r- and ﹡l- correspond not only with Tibeto-Burman r- and l-, but also with br-, gr-, dr-, and bl-, gl-. The latter correspond also with Old Chinese voiced initial consonants at the same time. On the basis of Sino-Tibetan cognates and Tibeto-Burman morphological models, this paper proposes that the former did not have prefixes in Proto-Chinese, whereas the latter did. The prefixes in Proto-Chinese (such as ﹡N-, ﹡s-, ﹡m- etc.) were lost after having exerted certain influences on some of the initial consonants. At about the same period, Proto-Chinese non-prefixed voiced stops before ﹡r- and ﹡l- were also lost. However, the prefixed voiced stops were preserved. The reconstructions proposed in this paper attempt to account for the influences of the prefixes on the initial consonants and their subsequent lost. In the concluding remarks this paper summarizes the sound changes of the consonant clusters with -r- and -l- as the second elements from Proto-Sino-Tibetan down to Middle Chinese.