Children with specific language impairment (SLI) are particularly sensitive to phonological complexity in their language. Their performance drops when there are specific phonological structures or when complexity increases. A nonword repetition (NWR) test, which aims to assess the phonology of bilingual speakers with and without SLI, should include phonological properties that are independent of the language and phonological properties whose complexity is quantifiable. The methodology and constraints related to the creation of a NWR test named LITMUS-NWR-FRENCH, which combines these two objectives, are presented. This task was tested on a population of 67 children, 5.5 to 8.5 years old, bilingual and monolingual, with and without SLI, having in common French as L1 or L2. Results show that the LITMUS-NWR-FRENCH task differentiates between children with and without SLI in the context of bilingualism. It also shows the influence and importance of phonological complexity in children with SLI.