a b s t r a c tWe construct explicit Drinfel'd twists for the generalized Cartan type S Lie algebras and obtain the corresponding quantizations. By modular reduction and base changes, we obtain certain quantizations of the restricted universal enveloping algebra u(S(n; 1)) in characteristic p. They are new Hopf algebras of truncated p-polynomial noncommutative and noncocommutative deformation of dimension p 1+(n−1)(p n −1) , which contain the well-known Radford algebra (Radford (1977) [23]) as a Hopf subalgebra. As a by-product, we also get some Jordanian quantizations for sl n .In [15], the authors studied quantizations both for the generalized Witt algebra W in characteristic 0 and for the Jacobson-Witt algebra W(n; 1) in characteristic p. In the present paper, we continue to treat the same questions both for the generalized Cartan type S Lie algebras in characteristic 0 (for the definition, see [4]) and for the restricted simple special algebras S(n; 1) in the modular case (for the definition, see [26,27]). Our techniques are somewhat different from those in [15] and the method of constructing the twist can be generalized to other Cartan type Lie algebras.We survey some previous related work. In [6], Drinfel'd raised the question of the existence of a universal quantization for Lie bialgebras. Etingof and Kazhdan gave a positive answer to this question in [8,9], where the Lie bialgebras that they considered including finite-and infinite-dimensional ones are the Lie algebras defined by generalized Cartan matrices. Enriquez and Halbout showed that any coboundary Lie bialgebra, in principle, can be quantized via a certain EtingofKazhdan quantization functor [7], and Geer extended Etingof and Kazhdan's work from Lie bialgebra to the setting of Lie superbialgebras [11]. After the work [8,9], it is natural to consider the quantizations of Cartan type Lie algebras which are defined by differential operators. In 2004, Grunspan [14] obtained the quantization of the (infinite-dimensional) Witt algebra W in characteristic 0 using the twist found by Giaquinto and Zhang [12], but his approach didn't work for the quantum version of its simple modular Witt algebra W(1; 1) in characteristic p. The authors in [15] obtained the quantizations of the generalized Witt algebra W in characteristic 0 and the Jacobson-Witt algebra W(n; 1) in characteristic p; they are new families of noncommutative and noncocommutative Hopf algebras of dimension p 1+np n in characteristic p, while in the rank 1 case, the work recovered Grunspan's work in characteristic 0 and gave the required quantum version in characteristic p.Although, in principle, the possibility of quantizing an arbitrary Lie bialgebra has been proved, an explicit formulation of Hopf operations remains nontrivial. In particular, only a few kinds of twists were known with an explicit expression; see [12,19,22,24] and the references therein. In this research, we start with an explicit Drinfel'd twist due to [12,14], which, we found recently, is essentially a variation of the Jorda...